Electric current is measured by: A. Commutator B. Anemometer C. Ammeter D. Voltmeter

The correct answer is C. Ammeter.

An ammeter is a measuring instrument used to measure electric current in an electric circuit. It is an essential tool for electricians and other electrical workers.

A commutator is a device that reverses the current in the windings of a motor or generator. It is used to keep the motor or generator from spinning in the wrong direction.

An anemometer is an instrument used to measure wind speed. It is often used in meteorology and aviation.

A voltmeter is an instrument used to measure voltage. It is used to test the voltage of batteries, power supplies, and other electrical devices.