正解:D
Unannounced testing is the most accurate way to assess the effectiveness of controls, as it simulates a real- world scenario and does not allow the staff to prepare or modify their behavior in advance. Mature change management processes, senior management support, and well-defined security policies are all important factors for establishing and maintaining a strong security posture, but they do not directly measure the performance of controls. References = CISM Review Manual, 16th Edition, page 149. CISM Questions, Answers & Explanations Database, question ID 1003.