Least privilege is the best way to reduce the likelihood of an individual performing a potentially harmful action as the result of unnecessary entitlement, because it limits the access and permissions of the individual to the minimum level that is required to perform their role or function, and prevents the individual from accessing or modifying the resources or data that are not relevant or authorized. An entitlement is a right or privilege that grants an individual the ability to access or use a resource or data, such as a file, a system, or an application. An unnecessary entitlement is an entitlement that is not needed or justified for the individual's role or function, and may pose a risk of unauthorized or inappropriate access or use of the resource or data. A potentially harmful action is an action that may cause harm or damage to the organization or its objectives, such as a data breach, a fraud, or a sabotage. Least privilege is thebest way, as it helps to minimize the exposure and impact of the unnecessary entitlement, and to reduce the likelihood and severity of the potentially harmful action. Application monitoring, separation of duty, and nonrepudiation are all possible ways to reduce the likelihoodof an individual performing a potentially harmful action as the result of unnecessary entitlement, but they are not the best way, as they do not directly address the unnecessary entitlement, and may not prevent the potentially harmful action. References = Risk and Information Systems Control Study Manual, Chapter 5, Section 5.3.2, page 200