Which of the following individuals is responsible for ensuring the security posture of the organization's information system? Response:

The Authorizing Official (AO) is a senior federal agency official with the authority to formally assume responsibility for operating an information system at an acceptable level of risk. This role involves reviewing the security documentation and assessment results, making a risk determination, and granting an Authorization to Operate (ATO) for the system, thereby ensuring its security posture is acceptable.

The Chief Information Officer (CIO) is responsible for overall IT strategy and management, but the AO is specifically responsible for the risk acceptance and security posture of individual systems.

A Security Control Assessor (SCA) evaluates the security controls, but does not ultimately authorize the system to operate or bear the responsibility for its security posture.

A Common Control Provider is responsible for implementing and managing common controls shared by multiple systems, but the AO still makes the risk decision for systems using those controls.