_________ system keeps a careful check on the changes taking place in the organization and in the environment and helps to review and revise the standards in light of such changes.

Option 1: Good Personnel Management -> Focuses on managing human resources, recruitment, and employee development, not on monitoring organizational changes and revising standards.

Option 2: Effective and Efficient Coordination -> Ensures different departments work together harmoniously, but doesn't primarily deal with monitoring changes and revising standards.

Option 3: Efficient Control Mechanism -> Systematically monitors performance, tracks changes in the organization and environment, compares actual results with standards, and facilitates revision of standards when needed.

Option 4: Good Compensation and Promotion -> Deals with employee rewards and career advancement systems, not with monitoring organizational changes or revising standards.

Hence, Option 3: Efficient Control Mechanism -> A control mechanism is specifically designed to measure performance, monitor changes in both internal and external environments, detect deviations from standards, and most importantly, provide feedback to review and revise standards when circumstances change. This is a fundamental management control function that ensures standards remain relevant and achievable. -> correct