The capacity of a battery is expressed in terms of

current rating
voltage rating
ampere-hour rating
none of the above

The correct answer is C. ampere-hour rating.

A battery’s capacity is the amount of electrical energy it can store. It is measured in ampere-hours (Ah). One ampere-hour is the amount of current that a battery can deliver for one hour at a constant voltage.

The current rating of a battery is the maximum current that it can safely deliver. The voltage rating of a battery is the maximum voltage that it can safely produce.

Neither the current rating nor the voltage rating of a battery is a measure of its capacity.