1. OCEG, "GRC Capability Model," Version 3.5, OCEG (2021).
Page 70, Section 4.3, "Provide Assurance": This section defines assurance as measures that "build confidence and trust that an organization will meet its objectives." It explicitly states that assurance is provided by roles like internal audit, which review the effectiveness of controls and actions. This supports that the purpose of those controls is to be the subject of assurance services.
Page 62, Section 3.3, "Perform Proactive Actions": This section describes controls as "the specific actions taken to increase the likelihood that a desired outcome will be realized and an undesired outcome will be prevented." These are the very actions that assurance personnel evaluate.
2. The Institute of Internal Auditors (IIA) Research Foundation, "Internal Audit Capability Model (IA-CM) for the Public Sector," (2009).
Page 1, Introduction: The document states the IA-CM "provides a framework for assessing the capabilities of an internal audit activity... to enhance its professionalism, performance, and, ultimately, its value to the organization." The entire model, which encompasses the processes and controls of an audit function, is designed to improve the delivery of assurance services, aligning directly with option A.