Residual system access is the risk that the customer service representatives who are transferred to the sales department may still have access to the systems or applications that they used in their previous role, which may not be relevant or authorized for their new role.

The access control manager is the person or function who is responsible for defining, implementing, and maintaining the policies and procedures for granting, modifying, reviewing, and revoking access rights to the systems or applications, based on the principle of least privilege and the segregation of duties.

The access control manager is responsible for mitigating the risk associated with residual system access, by ensuring that the access rights of the customer service representatives are updated or removed according to their new role and responsibilities, and that the access changes are documented and approved by the appropriate authorities.

The other options are not responsible for mitigating the risk associated with residual system access. They are either irrelevant or less effective than the access control manager.

The references for this answer are:

Risk IT Framework, page 26

Information Technology & Security, page 20

Risk Scenarios Starter Pack, page 18