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

The organizational risk register is the most useful for an information security manager when determining the need to escalate an incident to senior management because it contains a list of identified risks to the organization, their likelihood and impact, and their predefined risk thresholds or targets, which can help the information security manager assess the severity and urgency of the incident and decide whether it requires senior management's attention or action. Incident management procedures are not very useful for this purpose because they do not provide any specific criteria or guidance on when to escalate an incident to senior management. Incident management policy is not very useful for this purpose because it does not provide any specific criteria or guidance on when to escalate an incident to senior management. System risk assessment is not very useful for this purpose because it does not reflect the current risk exposure or status of the organization as a whole. References: https://www.isaca.org/resources/isaca-journal/issues/2016/volume-6
/how-to-measure-the-effectiveness-of-information-security-using-iso-27004 https://www.isaca.org/resources
/isaca-journal/issues/2017/volume-5/incident-response-lessons-learned

Continuous monitoring is the most effective way to identify changes in an information security environment, as it provides ongoing awareness of the security status, vulnerabilities, and threats that may affect the organization's information assets and risk posture. Continuous monitoring also helps to evaluate the performance and effectiveness of the security controls and processes, and to detect and respond to any deviations or incidents in a timely manner. (From CISM Review Manual 15th Edition and NIST Special Publication 800-1371) References: CISM Review Manual 15th Edition, page 181, section 4.3.2.4; NIST Special Publication 800-
1371, page 1, section 1.1.