Alternating current is measured by

induction ammeter
permanent magnet type ammeter
electrostatic ammeter
moving iron repulsion type voltmeter

The correct answer is A. Induction ammeter.

An induction ammeter is a type of ammeter that measures alternating current (AC). It works by using the principle of electromagnetic induction to create a current in a secondary coil that is proportional to the current in the primary coil. The secondary coil is connected to a meter that measures the current.

A permanent magnet type ammeter is a type of ammeter that measures direct current (DC). It works by using the principle of magnetism to create a current in a coil that is proportional to the current in the circuit. The current in the coil is then measured by a meter.

An electrostatic ammeter is a type of ammeter that measures DC. It works by using the principle of electrostatics to create a current in a coil that is proportional to the current in the circuit. The current in the coil is then measured by a meter.

A moving iron repulsion type voltmeter is a type of voltmeter that measures AC. It works by using the principle of magnetic repulsion to create a current in a coil that is proportional to the voltage in the circuit. The current in the coil is then measured by a meter.

In conclusion, the correct answer is A. Induction ammeter.