What must be lowered over the side after passing the heaving line?

The correct choice is to lower the eductor over the side after passing the heaving line. An eductor is a device used to create a vacuum that can draw water or other substances and is often employed in maritime operations to remove water from flooded compartments or to assist with dewatering during rescue operations. Deploying an eductor can be crucial after establishing communication and passing the heaving line, which enables a safe and effective means of managing water on board or in a distress situation.

In scenarios where a heaving line is passed, the intent is usually to allow the crew to maintain continuous connection and to facilitate further operations, such as dewatering. The eductor's readiness is essential after the heaving line is passed because it may be needed immediately to combat flooding or assist with the safe recovery of personnel or vessels in distress.

The other options, although they may have functions related to rescue or safety, are not typically deployed in the immediate aftermath of passing a heaving line in maritime operations. Rescue buoys are generally used for flotation and life-saving, pump lines facilitate the movement of liquid but may not be as immediately relevant as the eductor in this context, and crossover lines are used for different purposes such as connecting equipment rather than direct life-saving operations