Which type of timer accumulates the total amount of time the instruction has been energized and retains this value even when de-energized?

A retentive timer is designed to accumulate the total amount of time an instruction is energized while holding onto that value even after it is de-energized. This functionality is crucial in applications where it is important to measure time continuously over multiple cycles of operation. For example, if a process is interrupted and then restarted, a retentive timer will continue from the last accumulated time, allowing for accurate tracking without resetting.

In contrast, a non-retentive timer resets its accumulated time to zero when the instruction is de-energized. This means it cannot provide a continuous measurement through interruptions. Interval and delay timers serve specific purposes related to timing operations, but they do not specifically retain the time value after deactivation in the same way a retentive timer does. Thus, the definition and functionality associated with a retentive timer make it the correct answer in this context.