The correct answer is: D. Integrating
Integrating instruments are those which measure the total quantity of electricity delivered in a particular time. They are used to measure the total energy consumed by a load, or the total charge that has passed through a circuit.
Absolute instruments are those which can measure the quantity of electricity without the need for any calibration. They are typically used in research and development applications where the highest accuracy is required.
Indicating instruments are those which provide a visual indication of the quantity of electricity being measured. They are typically used in industrial applications where a simple indication of the current or voltage is required.
Recording instruments are those which provide a permanent record of the quantity of electricity being measured. They are typically used in applications where it is important to monitor the electrical usage over time.