Final answer:
Athwartships is a nautical term describing something that is situated 'across' or 'from side to side' on a ship, perpendicular to its fore-and-aft line.
Step-by-step explanation:
The nautical term "Athwartships" refers to anything that is situated 'across' or 'from side to side' aboard a vessel relative to the keel. If something is described as athwartships, it is oriented in a direction that is perpendicular to the ship's fore-and-aft line. To be specific, the correct definition for athwartships is B. Across the ship.