Capacity of a battery.is expressed in

Ah
Vh
Wh
kWh

The correct answer is C. Wh.

A battery’s capacity is the amount of energy it can store. It is measured in watt-hours (Wh). One watt-hour is equal to one watt of power for one hour. For example, a battery with a capacity of 100 Wh can provide 100 watts of power for one hour, or 1 watt of power for 100 hours.

The other options are incorrect. Ampere-hour (Ah) is a measure of the battery’s current capacity. Voltage (V) is a measure of the battery’s electrical potential. Kilovolt-hour (kWh) is a measure of the battery’s energy capacity, but it is a much larger unit than Wh.