What are the hammer, anvil, and stirrup?

A) tiny bones located in the middle ear
B) types of cones on the retina
C) types of sound that most people can detect
D) words often used by audiologists in testing for hearing difficulties

Hammer

A tool typically used to drive nails into, or pull them out of, some other object, generally involving a handle attached to a heavy head.

Anvil

a heavy iron block typically used in forging or metalworking as a surface upon which metal can be hammered and shaped.

Stirrup

A ring or frame, hanging down from the saddle of a horse, for a rider's foot.