Final answer:
The Officer of the Deck is responsible for maintaining the deck log on a underway ship, as the deck log is a detailed record of events and decisions made while the ship is sailing.
Step-by-step explanation:
On a ship that is underway, the person who is responsible for maintaining the deck log is the Officer of the Deck (Option C). The deck log serves as a detailed record of all significant events and key operational decisions made while the ship is in motion.
The Captain and the Chief Engineer, while holding important positions, do not directly oversee the maintenance of the deck log. Likewise, the Boatswain, who is in charge of the ship's crew and equipment, does not hold this responsibility either. The role of maintaining the deck log falls under the Officer of the Deck's duties because this position typically involves overseeing the navigation and safety of the vessel, which coincides with the purpose of the deck log.
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