A Business Continuity Plan (BCP) is considered to be valid when it has been validated by realistic exercises.
A BCP is a part of a BCP/DRP that focuses on ensuring the continuous operation of the organization's critical business functions and processes during and after a disruption or disaster. A BCP should include various components, such as:
* Business impact analysis: a process that identifies and prioritizes the critical business functions and processes, and assesses the potential impacts and risks of a disruption or disaster on them
* Recovery strategies: a process that defines and selects the appropriate methods and resources to recover the critical business functions and processes, such as alternate sites, backup systems, or recovery teams
* BCP document: a document that outlines and details the scope, purpose, and features of the BCP, such as the roles and responsibilities, the recovery procedures, and the contact information
* Testing, training, and exercises: a process that evaluates and validates the effectiveness and readiness of the BCP, and educates and trains the relevant stakeholders, such as the staff, the management, and the customers, on the BCP and their roles and responsibilities
* Maintenance and review: a process that monitors and updates the BCP, and addresses any changes or issues that might affect the BCP, such as the business requirements, the threat landscape, or the feedback and lessons learned A BCP is considered to be valid when it has been validated by realistic exercises, because it can ensure that the BCP is practical and applicable, and that it can achieve the desired outcomes and objectives in a real-life scenario. Realistic exercises are a type of testing, training, and exercises that involve performing and practicing the BCP with the relevant stakeholders, using simulated or hypothetical scenarios, such as a fire drill, a power outage, or a cyberattack. Realistic exercises can provide several benefits, such as:
* Improving the confidence and competence of the organization and its staff in handling a disruption or disaster
* Enhancing the performance and efficiency of the organization and its systems in recovering from a disruption or disaster
* Increasing the compliance and alignment of the organization and its plans with the internal or external requirements and standards
* Facilitating the monitoring and improvement of the organization and its plans by identifying and addressing any gaps, issues, or risks The other options are not the criteria for considering a BCP to be valid, but rather the steps or parties that are involved in developing or approving a BCP. When it has been validated by the Business Continuity (BC) manager is not a criterion for considering a BCP to be valid, but rather a step that is involved in developing a BCP. The BC manager is the person who is responsible for overseeing and coordinating the BCP activities and processes, such as the business impact analysis, the recovery strategies, the BCP document, the testing, training, and exercises, and the maintenance and review. The BC manager can validate the BCP by reviewing and verifying the BCP components and outcomes, and ensuring that they meet the BCP standards and objectives. However, the validation by the BC manager is not enough to consider the BCP to be valid, as it does not test or demonstrate the BCP in a realistic scenario. When it has been validated by the board of directors is not a criterion for considering a BCP to be valid, but rather a party that is involved in approving a BCP. The board of directors is the group of people who are elected by the shareholders to represent their interests and to oversee the strategic direction and governance of the organization. The board of directors can approve the BCP by endorsing and supporting the BCP components and outcomes, and allocating the necessary resources and funds for the BCP. However, the approval by the board of directors is not enough to consider the BCP to be valid, as it does not test or demonstrate the BCP in a realistic scenario. When it has been validated by all threat scenarios is not a criterion for considering a BCP to be valid, but rather an unrealistic or impossible expectation for validating a BCP. A threat scenario is a description or a simulation of a possible or potential disruption or disaster that might affect the organization's critical business functions and processes, such as a natural hazard, a human error, or a technical failure. A threat scenario can be used to test and validate the BCP by measuring and evaluating the BCP's performance and effectiveness in responding and recovering from the disruption or disaster. However, it is not possible or feasible to validate the BCP by all threat scenarios, as there are too many or unknown threat scenarios that might occur, and some threat scenarios might be too severe or complex to simulate or test. Therefore, the BCP should be validated by the most likely or relevant threat scenarios, and not by all threat scenarios.

It's interesting to note that the steps to resume normal processing operations will be different than the steps of the recovery plan; that is, the least critical work should be brought back first to the primary site.
The most important point above in the steps would be to move the least critical items or resources back to the primary site first. This way you can ensure that the site was really well prepared and that all is working fine.
Before that first step would be done, you would get the green light from the salvage team that it is fine to move back to the primary site. The first step after getting the green light would be to move the least critical elements first.
As stated in the Shon Harris book: The least critical functions should be moved back first, so if there are issues in network configurations or connectivity, or important steps were not carried out, the critical operations of the company are not negatively affected. Why go through the trouble of moving the most critical systems and operations to a safe and stable site, only to return it to a main site that is untested? Let the less critical departments act as the canary. If they survive, then move over the more critical components of the company.
When it is time for the company to move back into its original site or a new site, the company enters the reconstitution phase. A company is not out of an emergency state until it is back in operation at the original primary site or a new site that was constructed to replace the primary site, because the company is always vulnerable while operating in a backup facility.
Many logistical issues need to be considered as to when a company must return from the alternate site to the original site. The following lists a few of these issues:
Ensuring the safety of employees
Ensuring an adequate environment is provided (power, facility infrastructure, water, HVAC)
Ensuring that the necessary equipment and supplies are present and in working order
Ensuring proper communications and connectivity methods are working
Properly testing the new environment
Once the coordinator, management, and salvage team sign off on the readiness of the facility, the salvage team should carry out the following steps:
Back up data from the alternate site and restore it within the new facility.
Carefully terminate contingency operations.
Securely transport equipment and personnel to the new facility.
All other choices are not the correct answer.
Reference(s) used for this question:
Harris, Shon (2012-10-25). CISSP All-in-One Exam Guide, 6th Edition (Kindle Location 19389).
McGraw-Hill. Kindle Edition.
and
KRUTZ, Ronald L. & VINES, Russel D., The CISSP Prep Guide: Mastering the Ten Domains of Computer Security, John Wiley & Sons, 2001, Page 290.