Answer:
The correct option is the piston
Explanation:
A steam engine is an engine that uses steam or vapour as it's working fluid. In steam engines, the pressure produced by the steam is used to move a piston inside a cylinder. The piston moves back and forth causing a rotary motion during the course of the engine's work. This steam is usually produced in a boiler (and later supplied from there) somewhere inside the engine. Steam engines were used in some production factories and they were also used in ships and locomotive trains.
