Which of these is an example of a composite material?

A. Wood planks used as beams to support roofs

B. Aluminum for the outer layer of an airplane

C. Fiberglass (a polymer that's is reinforced with embedded glass fibers)

D. Steel cables designed to be lightweight and strong

C. Fiberglass is composite material.

Explanation:

Wood is natural material, which is made by biochemical processes.

Aluminum is a chemical element, a sort of metal.

Steel is firm alloy of iron and carbon.

Composite materials are one that are built from several firm materials combined together. Only fiberglass fits to this description.