Final answer:
A vessel not at anchor, made fast to the shore, or aground is described as 'underway'. It indicates that the ship is moving or capable of moving through the water, akin to a car that is actively driving on the road.
Step-by-step explanation:
The condition that describes a vessel not at anchor, made fast to the shore, or aground is underway. When a ship is underway, it means that it is not attached to the shore, not anchored, and not on the ground. It may be moving through the water powered by its engines or floating due to the currents and wind.
An example to illustrate this would be a car which is not parked, not stopped at traffic lights, or not stuck in traffic; it would be equivalent to a car that is in motion, which is the scenario 'b' represents.
Conditions like being free-floating or drifting could also describe a vessel that is not anchored or tied to the shore, but these terms don't necessarily indicate that the vessel is being propelled or controlled. 'Underway' is used specifically to imply that the vessel is making way through the water, regardless of whether it is being propelled or is under control