Explanation
According to the CISM Review Manual, a business impact analysis (BIA) is the most useful tool when determining the business continuity strategy for a large organization's data center, as it helps to identify and prioritize the critical business processes and resources that depend on the data center, and the impact of their disruption or loss. A BIA also provides the basis for defining the recovery time objectives (RTOs) and recovery point objectives (RPOs) for the data center, which guide the selection of the appropriate business continuity strategy.
References = CISM Review Manual, 27th Edition, Chapter 3, Section 3.5.2, page 1511.

Comprehensive and Detailed Explanation: Employee accountability is the degree to which employees are responsible for their actions and outcomes related to information security. It reflects the extent to which employees understand their roles and responsibilities, follow the policies and procedures, report incidents and breaches, and comply with legal and regulatory requirements. Embedding security responsibilities into job descriptions helps to clarify the expectations and obligations of employees, as well as the consequences of non-compliance or negligence. It also helps to align the security objectives with the business goals and strategies, and to foster a culture of security awareness and responsibility.
References: 1: CISM Review Manual, 15th Edition, Chapter 3, Section 3.2.1.2

In a major disaster, staff can be injured or can be prevented from traveling to the hot site, so technical skills and business knowledge can be lost. It is therefore critical to maintain an updated copy of the detailed recovery plan at an offsite location. Continuity of the business requires adequate network redundancy, hot site infrastructure that is certified as compatible and clear criteria for declaring a disaster. Ideally, the business continuity program addresses all of these satisfactorily. However, in a disaster situation, where all these elements are present, but without the detailed technical plan, business recovery will be seriously impaired.

The best starting point for a newly hired information security manager who has been tasked with identifying and addressing network vulnerabilities is C. Penetration testing. This is because penetration testing is a method of simulating real-world attacks on a network to evaluate its security posture and identify any weaknesses or gaps that could be exploited by malicious actors. Penetration testing can help the information security manager to assess the effectiveness of the existing controls, prioritize the remediation efforts, and demonstrate compliance with the relevant standards and regulations. Penetration testing can also provide valuable insights into the network architecture, configuration, and behavior, as well as the potential impact and likelihood of different types of attacks.
References = CISM Review Manual 15th Edition, Chapter 4, Section 4.2.1, page 2091; CISM Review Questions, Answers & Explanations Manual 9th Edition, Question 50, page 14