• Unique value
• Necessary value
• Intrinsic value
• Actual value

The correct answer is: Actual value

Explanation: In value-centric measurement strategies, the most commonly used value definition is the “actual value.” These strategies allow advertisers to assign and optimize values to consumer activities. The value, which is usually transaction revenue or profit, is realized at the time of conversion. This process involves identifying critical conversion activities, defining their values, and capturing or calculating these values upon conversion. It’s essential to aim for an evolving strategy, improving over time as new solutions and consumer insights emerge.