If an alternator is to be inactive for a considerable period of time, which of the following actions should be taken? A. It should be disconnected from the prime mover and raised off its bearing supports. B. Insulation resistance readings should be taken weekly to ensure resistance is not deteriorating. C. The brushes should be lifted off the slip rings to prevent pitting of the metal by electrolytic action. D. The windings and collector rings should be protected with a thin coat of grease or oil.