Final answer:
The responsibility of ensuring all deck watch stations are manned with qualified personnel while underway falls under the Officer of the Deck.
Step-by-step explanation:
The correct answer is A. Officer of the Deck. When underway, the Officer of the Deck is responsible for ensuring all deck watch stations are manned with qualified personnel. The Officer of the Deck is in charge of the overall navigation and safety of the ship or vessel. They coordinate with the Quartermaster of the Watch to maintain a proper lookout and ensure all watch stations are properly staffed.
The OOD is in charge of the ship's operations and safety while underway, which includes maintaining the watch schedule and ensuring that each watch station is staffed with capable and qualified personnel. This role is vital to maintaining the efficiency and security of a ship's operations at sea.