The eradication phase of an incident response plan is where the root cause of the incident is determined and eliminated. This phase involves identifying and removing all traces of the malicious activity from the affected systems and restoring them to a secure state.
References = NIST SP 800-61 Revision 2, CISM Review Manual 15th Edition

Verified answer: According to the CISM Review Manual, 15th Edition, Chapter 3, Section 3.2.1.3, "The appropriate risk treatment option is decided by the chief information security officer (CISO) or the designated risk owner."1 The CISO is the senior executive who is responsible for overseeing and managing the information security program of an organization. The CISO has the authority and expertise to assess the risks, determine the risk appetite and tolerance levels, and select the most suitable risk treatment options for each risk. The CISO also has the accountability and responsibility for implementing, monitoring, and reporting on the risk treatment activities.
References: 1: CISM Review Manual, 15th Edition, Chapter 3, Section 3.2.1.3

Comprehensive and Detailed Explanation = The risk owner is the person or entity with the accountability and authority to manage a risk. The risk owner should have the decision-making authority and the ability to allocate resources for risk treatment and related control activities. The risk owner should also be responsible for monitoring and reporting on the risk, but these are not the most important considerations when assigning a risk owner. The risk owner may not have adequate knowledge of risk treatment and related control activities, but can delegate or consult with experts as needed. The risk owner should also have sufficient time for managing the risk effectively, but this is not a prerequisite for assigning a risk owner.
References =
* CISM Review Manual 15th Edition, page 76
* CISM Practice Quiz, question 4171

The information security manager's primary focus during the development of a critical system storing highly confidential data should be ensuring the amount of residual risk is acceptable. Residual risk is the level of cyber risk remaining after all the security controls are accounted for, any threats have been addressed and the organization is meeting security standards. It's the risk that slips through the cracks of the system. For a critical system storing highly confidential data, the residual risk should be as low as possible, and within the organization's risk appetite and tolerance. The information security manager should monitor and review the residual risk throughout the system development life cycle, and ensure that it is communicated and approved by the appropriate stakeholders. The other options are not the primary focus, although they may be part of the security objectives and activities. Reducing the number of vulnerabilities detected is a desirable outcome, but it does not necessarily mean that the residual risk is acceptable, as some vulnerabilities may have a higher impact or likelihood than others. Avoiding identified system threats is a preventive measure, but it does not account for unknown or emerging threats that may pose a residual risk to the system. Complying with regulatory requirements is a mandatory obligation, but it does not guarantee that the residual risk is acceptable, as regulations may not cover all aspects of security or reflect the specific context and needs of the organization.