Which of the following accurately describes a "line" in naval use?

In naval terminology, a "line" specifically refers to a length of rope that is cut and assigned a particular function, such as securing a ship, hoisting sails, or handling cargo. This definition encompasses a wide variety of ropes used onboard vessels, where each type may be designated for specific tasks. For instance, a line can be tied off to secure a boat at a dock or used to maneuver a sail. Understanding this terminology is crucial for effective communication and operations on a ship, as sailors need to know the specific roles lines play in various maritime activities.

The other choices do not accurately reflect the definition of a line in this context. Equipment used for navigation relates more to instruments like compasses or GPS units rather than ropes. The term does not apply to military targets or components of the ship's electrical system, which belong to very different categories of naval operations. Thus, the choice emphasizing a length of rope assigned a function best captures the essence of what a line is in naval use.