The primary purpose for continuous monitoring of security controls is to ensure the effectiveness of controls. This involves regularly assessing the controls to ensure that they are meeting their intended objectives, and that any potential weaknesses are identified and addressed. Continuous monitoring also helps to ensure that control gaps are minimized, and that systems are available and aligned with compliance requirements.

The results of a risk assessment would best enable an informed decision by senior management when developing a business case to justify an information security investment. A risk assessment will help to identify and prioritize the threats and vulnerabilities that affect the organization's assets and processes, as well as the potential impact and likelihood of occurrence. A risk assessment will also provide a basis for selecting and evaluating the effectiveness of controls to mitigate the risks. According to CISA, developing a business case for security will be based on an in-depth understanding of organizational vulnerabilities, operational priorities, and return on investment1. The information security strategy, losses due to security incidents, and security investment trends in the industry are possible inputs or outputs of a risk assessment, but they are not sufficient to enable an informed decision by senior management. Reference: 1: The Business Case for Security - CISA 2: The Business Case for Security | CISA 3: #HowTo: Build a Business Case for Cybersecurity Investment 4: Making the Business Case for Information Security

The explanation given in the manual is:
Incident classification criteria enable an organization to prioritize incidents based on their impact and urgency. This allows for an optimized allocation of recovery resources to minimize business disruption and ensure timely restoration of normal operations. The other choices are benefits of incident management but not directly related to incident classification criteria.