The Master of a vessel shall make sure the EPIRB is tested __________. (small passenger vessel regulations)

Correct Answer: Option D — monthly

46 CFR 185.510 requires the Master to ensure the Emergency Position Indicating Radio Beacon (EPIRB) is tested monthly. This routine maintenance ensures the battery and internal circuitry are functioning correctly, guaranteeing the device will transmit a distress signal effectively if the vessel encounters a life-threatening emergency at sea.