Composite cylinders are made from a combination of which materials?

• A. Aluminum and steel
• B. wood and ceramic
• C. fiberglass or carbon fibers and a plastic resin
• D. glass fibers and epoxy

Answer: (C)

Composite cylinders are built from reinforcing fibers embedded in a plastic resin matrix. The fibers—such as fiberglass or carbon fibers—provide high strength and stiffness, while the resin binds the fibers, transfers load, and protects them from moisture and chemicals. This combination yields a lightweight, strong, and corrosion-resistant container, which is why these cylinders are favored for propane storage.

Aluminum and steel are metals, not composites, so they don’t illustrate the fiber-reinforced polymer concept. Wood and ceramic aren’t used to make propane cylinders in practice. The example of glass fibers with epoxy is actually a specific case of the general idea (glass fibers in a resin), but describing the materials as fiberglass or carbon fibers with a plastic resin covers the broader and most common implementations.