From which materials can piston rings be made?

The correct answer highlights the appropriate materials commonly used in the manufacturing of piston rings, which are crucial components in an engine. Piston rings are designed to seal the combustion chamber, control oil consumption, and facilitate heat transfer from the piston to the cylinder wall.

Cast iron and ductile cast iron are widely used due to their excellent wear resistance and ability to withstand high temperatures, making them ideal for the harsh conditions within an engine. Steel alloys, including chrome-plated variations, are also favored for their strength and durability. Stainless steel can provide corrosion resistance and is sometimes used in performance applications where enhanced properties are needed.

While other options include materials that are not typically used in piston rings, the choices reflect a fundamental understanding that piston rings require materials that maintain integrity under extreme heat and pressure, while also providing good wear resistance and proper sealing capabilities. Thus, the selection of materials in option C aligns perfectly with industry standards and practices for piston ring design and functionality.