A steam engine is an example of a (n)

a. external combustion engine.

b. internal combustion engine.

c. four-stroke engine.

d. eight-cylinder engine.

A steam engine is an example of an "external combustible engine." A steam engine works by using steam as the main working fluids. The steam is separated from the combustion products. In some cases, geothermal and solar power can also be used. The correct answer is A.