What is a measure used to assess changes in system behavior and operational environment tied to the attainment of an objective?

The correct choice is Measure of Effectiveness. This measure is specifically designed to evaluate how well an operation or system achieves its intended objectives. It focuses on assessing the impact of actions taken and the changes in behavior or conditions resulting from those actions.

In the context of military operations, for example, measures of effectiveness help determine if the objectives of a mission—such as neutralizing a threat or securing an area—are being met. These measures provide valuable insight into the effectiveness of strategies or tactics deployed during operations. By analyzing these metrics, military leaders can make informed decisions about ongoing strategies and whether adjustments are necessary to achieve desired outcomes.

While the other options may relate to various aspects of performance or operational assessments, they don’t encapsulate the specific focus of measuring how well an objective has been attained in terms of behavior changes in the environment or system.