Which of the following propulsor types would be used with unidirectional propulsion shafting rotation?

Correct Answer: Option B — Controllable-pitch propeller

Controllable-pitch propellers enable vessels to maneuver and reverse direction without changing the direction of shaft rotation. This is ideal for unidirectional prime movers, such as gas turbines or specific diesel engine configurations, where frequent starting and stopping or reversing gear engagement is undesirable.