Explanation
According to the CISM Review Manual, the most important metric to present to senior management when reporting on the performance of a risk mitigation initiative is the cost and associated risk reduction, as it demonstrates the value and effectiveness of the initiative in terms of reducing the likelihood and impact of the risk. The other metrics may be useful for comparison or analysis, but they do not directly measure the performance of the initiative.
References = CISM Review Manual, 27th Edition, Chapter 4, Section 4.3.2, page 2091.

Explanation
The CEO is the best able to influence the security culture within an organization because the CEO sets the tone and direction for the organization and has the authority and responsibility to ensure that the organization's objectives are aligned with its strategy. The CEO can also communicate the importance and value of information security to all stakeholders and foster a culture of security awareness and accountability. The CISO, CIO and COO are important roles in information security management, but they do not have the same level of influence and authority as the CEO. References = CISM Review Manual, 16th Edition, page 221; CISM Exam Content Outline, Domain 1, Task 12 The Chief Information Security Officer (CISO) is responsible for leading and coordinating an organization's information security program, and as such, is in a prime position to influence the security culture within the organization. The CISO is responsible for setting policies and standards, educating employees about security risks and best practices, and ensuring that the organization is taking appropriate measures to mitigate security risks. By demonstrating a strong commitment to information security, the CISO can help to create a security-aware culture within the organization.

Section: INFORMATION SECURITY GOVERNANCE

Section: INFORMATION SECURITY PROGRAM DEVELOPMENT