Which of the following is a direct measure of the power consumed in a circuit?

True power is the correct answer because it specifically quantifies the actual power consumed by a circuit to perform useful work over time. It is measured in watts (W) and represents the portion of electrical power that results in the energy being converted to work, such as lighting bulbs or running appliances. True power takes into account the phase difference between voltage and current, providing a clear picture of the energy being used effectively in the circuit.

In contrast, reactive power, measured in volt-amperes reactive (VAR), does not perform any useful work; instead, it represents energy that oscillates back and forth in the circuit, primarily within inductive and capacitive components. Apparent power, measured in volt-amperes (VA), is a combination of both true and reactive power, but it does not solely represent the power consumed for work. Input power is a vague term that can refer to the total power put into a system but does not specifically define the power consumed as true power does. Thus, true power is the most accurate and defined measurement for calculating the useful energy consumed in an electrical circuit.