Which term describes the stair-like structure on a ship that connects different levels?

The correct term that describes the stair-like structure on a ship that connects different levels is "ladders." In naval terminology, ladders refer specifically to the steep, vertical structures found on ships that function to allow crew members to move between decks. Unlike regular stairs commonly found in homes and buildings, ladders on ships are designed to save space and provide safer access in often confined areas.

Other options, such as steps and stairs, generally imply a structure with a less steep angle that is more comfortable for general use, which is not typical on ships. Ramps, on the other hand, pertain to an inclined surface that facilitates movement from one level to another but is not used to describe the vertical access structure between decks aboard a ship. Thus, when considering the context and specific usage within the maritime setting, "ladders" is the most accurate and appropriate term.