Correct Answer - Option 3 : integrating instruments
Integrating Instruments: These instruments record the consumption of the total quantity of electricity, energy etc. during a particular period of time. These instruments give reading for a specific period of time but no indication of reading for a particular instant of time.
Example: Ampere-hour meter, Energy meter, kilovolt ampere-hour meter
Indicating Instruments: These indicate the quantity being measured by means of a pointer that moves on a scale. These instruments indicate the instantaneous value of the electrical quantity being measured at the time at which it is being measured.
Example: Ammeter, Voltmeter, Wattmeter, Speedometer
Recording Instruments: These instruments record continuously the variation of any electrical quantity with respect to time. In principle, these are indicating instruments but so arranged that a permanent continuous record of the indication is made on a chart or dial.
Any electrical quantity like current, voltage can be recorded by a suitable recording mechanism.
Example: A potentiometric type of recorder used for monitoring temperature records the instantaneous temperatures on a strip chart recorder.