According to Coast Guard Regulations (46 CFR), when loading, or discharging oil in bulk at a dock, which of the following signals must be displayed?

Correct Answer: Option C — A red flag (day), red light (night)

Title 33 CFR 155.815 mandates that any vessel transferring bulk oil or hazardous materials at a dock must display a red flag (Day signal 'Bravo') during daylight and a red all-round electric light at night to warn approaching traffic.