Final answer:
The term that means toward the side of a ship sheltered from the wind, using up three vowels, is 'alee' (answer choice a).
Step-by-step explanation:
The word that means toward the side of a ship that's sheltered from the wind, and also uses up three vowels, is alee. This term is specifically used to describe the side of a ship that is away from the direction of the wind, often seen as the side that is more protected or sheltered. In the context of nautical terms, leeward is the direction downwind from a point, windward is the direction upwind, and lateral refers to the sides of an object or vessel, but not specifically related to wind direction.