With what device is the simplest method of controlling the terminal voltage of compound-wound DC generator?

Correct Answer: Option B — hand-operated field rheostat connected in series with the shunt field circuit

A hand-operated field rheostat connected in series with the shunt field circuit directly modifies total circuit resistance. This adjusts shunt field current, altering main flux strength and providing the simplest, most direct method to control terminal voltage on compound-wound DC generators.