Which of the following describes the construction material of acetylene cylinders?

Acetylene cylinders are constructed from steel due to the specific requirements for safely storing and transporting acetylene gas. Steel provides the necessary strength to withstand high pressure and ensures the structural integrity of the cylinder. The use of steel also allows for a certain level of robustness, which is critical when handling industrial gases that can be volatile.

Additionally, steel cylinders are often treated with protective coatings to prevent rust and corrosion, further enhancing their durability. This is vital because acetylene is a highly flammable gas, and the integrity of the cylinder is essential to prevent leaks that could lead to hazardous situations.

Other materials like aluminum, plastic, or composite materials do not meet the stringent safety standards necessary for high-pressure gas storage. They lack the necessary properties to ensure safety and durability in the conditions that acetylene cylinders are subjected to in various industrial applications.