Which of the following is an example of a composite material?

Fibreglass is indeed an example of a composite material because it consists of a polymer matrix (usually polyester or epoxy resin) reinforced with glass fibers. This combination results in a material that has enhanced strength, stiffness, and resistance to various environmental factors compared to its individual components. The glass fibers provide structural strength, while the resin binds them together and allows for shaping into various forms.

Composite materials are designed to combine desirable properties of different materials, resulting in improved performance for applications such as construction, automotive, and sporting goods. The other options listed, while they may be important materials in their own right, are not composites because they do not involve the combination of multiple materials to achieve superior properties.