What statement best represents the characteristics of an ullage tape and bob for the purposes of taking a vented tank sounding?

Correct Answer: Option C — The bob has a cupped end and floats on the surface of the liquid when lowered by the tape.

An ullage tape and bob are used to measure the distance from a reference point to the liquid surface. The bob features a cupped end to hold a small sample of the liquid, and it is designed to float on the surface to ensure an accurate measurement of the ullage space.