Before work may safely commence on a high voltage system, what must first be done after disconnection and isolation?

Correct Answer: Option C — The circuit must be tested and proved dead first with a live-line tester, then grounded.

Standard high voltage safety protocols mandated by IEEE 45 and marine electrical safe-working practices require verifying zero energy state with a live-line tester before applying grounds. This prevents accidental energization or flashover hazards to personnel prior to applying portable or fixed earthing devices.