The effectiveness of a control action plan’s implementation can be measured by the extent to which it achieves the desired risk reduction. A control action plan is a set of actions that are designed to address the root causes of a risk and mitigate its impact or likelihood. The best indicator of the effectiveness of a control action plan’s implementation is the reduced risk level, which means that the risk is either eliminated or brought within the acceptable range. The otheroptions are not the best indicators, because they do not directly reflect the risk reduction. Increased number of controls may not necessarily reduce the risk level, especially if the controls are not aligned with the risk causes, objectives, and priorities. Increased risk appetite may indicate a higher tolerance for risk, but it does not mean that the risk level has been reduced. Stakeholder commitment may facilitate the implementation of the control action plan, but it does not guarantee the effectiveness of the plan. References = Risk and Information Systems Control Study Manual, 7th Edition, Chapter 3: Risk Response, Section 3.2: Control Action Plan, p. 170-171.