An AC current can be produced by

Correct answer: (b) dynamo

Explanation

A dynamo generates current by rotating a coil within a magnetic field, working on Faraday's law of electromagnetic induction.

As the coil rotates, the changing magnetic flux reverses the current direction each half-turn, producing alternating current (AC).

A choke coil only opposes AC, and a transformer merely changes voltage of existing AC; neither produces it.