Final answer:
The Hull Identification Number (HIN) is the boat's equivalent of a serial number and refers to A) Boat serial number. It's a unique 12-character identifier used for registration and identification of vessels.
Step-by-step explanation:
The Hull Identification Number (HIN) refers to the boat's equivalent of a serial number, which is option A) Boat serial number. It is a unique identifier assigned to a vessel that allows for its identification. The HIN is typically found on the starboard side of the transom (the flat surface forming the stern of a boat) and is used for registration, identification in case the boat is stolen, and for safety recall notices. It is a 12-character number that includes information on the manufacturer, the boat's characteristics, and the model year. It does not refer to option B) Engine model number, C) GPS coordinates, or D) Radio frequency identification.