When bunkering at anchorage which of the following signals must be displayed?

Correct Answer: Option C — A red flag by day ONLY

Under USCG regulations and international maritime customs, a vessel bunkering at anchorage must fly the International Code Flag "B" (Bravo)—a red flag—by day. At anchorage, standard anchor lights are shown at night, making the red light requirement specific to dockside transfers.