According to the CISM Review Manual (Digital Version), page 5, information security culture is the set of values, attitudes, and behaviors that shape how an organization and its employees view and practice information security. Transforming the information security culture requires a change management process that involves the following steps: creating a sense of urgency, forming a powerful coalition, developing a vision and strategy, communicating the vision, empowering broad-based action, generating short-term wins, consolidating gains and producing more change, and anchoring new approaches in the culture1. Among the four options, strong management support is the best enabler for transforming the information security culture, as it can provide the necessary leadership, resources, sponsorship, and alignment for the change management process. Periodic compliance audits, robust technical security controls, and incentives for security incident reporting are important elements of information security, but they are not sufficient to change the culture without strong management support. References = 1: CISM Review Manual (Digital Version), page 5

The business client should be responsible for determining access levels to an application that processes client information, because the business client is the owner of the data and the primary stakeholder of the application. The business client has the best knowledge and understanding of the business requirements, objectives, and expectations of the application, and the sensitivity, value, and criticality of the data. The business client can also define the roles and responsibilities of the users and the access rights and privileges of the users based on the principle of least privilege and the principle of separation of duties. The business client can also monitor and review the access levels and the usage of the application, and ensure that the access levels are aligned with the organization's information security policies and standards.
The information security team, the identity and access management team, and the business unit management are all involved in the process of determining access levels to an application that processes client information, but they are not the primary responsible party. The information security team provides guidance, support, and oversight to the business client on the information security best practices, controls, and standards for the application, and ensures that the access levels are consistent with the organization's information security strategy and governance. The identity and access management team implements, maintains, and audits the access levels and the access control mechanisms for the application, and ensures that the access levels are compliant with the organization's identity and access management policies and procedures. The business unit management approves, authorizes, and sponsors the access levels and the access requests for the application, and ensures that the access levels are aligned with the business unit's goals and strategies. References = ISACA, CISM Review Manual, 16th Edition, 2020, pages 125-126, 129-130, 133-134, 137-138.
ISACA, CISM Review Questions, Answers & Explanations Database, 12th Edition, 2020, question ID 1037.

The best way to determine corrective actions after a major information security incident is to conduct a postmortem assessment, which is a systematic and structured review of the incident, its causes, its impacts, and its lessons learned. A postmortem assessment can help to identify the root causes of the incident, the strengths and weaknesses of the incident response process, the gaps and deficiencies in the security controls, and the opportunities for improvement and remediation. A postmortem assessment can also help to document the recommendations and action plans for preventing or minimizing the recurrence of similar incidents in the future.
References = CISM Review Manual, 16th Edition eBook1, Chapter 4: Information Security Incident Management, Section: Incident Response, Subsection: Postincident Activities, Page 211.