Composite cylinders are made from a combination of which materials?

Composite cylinders are made primarily from materials such as fiberglass and carbon fiber. These materials are used because they combine lightweight properties with high strength, making composite cylinders an excellent choice for storing LP-gas. The use of fiberglass and carbon fiber allows these cylinders to have a much higher pressure rating and durability compared to traditional metal cylinders, which enhances safety during storage and transport.

Each of the other choices contains materials that either do not provide the structural integrity required for pressurized applications or are not typically used together in the design of composite cylinders. Therefore, the correct combination of fiberglass and carbon fiber stands out as the appropriate answer for the composition of composite cylinders.