Which of the following is true of a carburetor backfire flame arrestor?

A carburetor backfire flame arrestor plays a crucial role in preventing flames from escaping back into the engine compartment of inboard gasoline engines. When an engine backfires, the flame can travel backwards through the carburetor, which may ignite any flammable materials present, increasing the risk of an explosion. The flame arrestor serves as a safety device that allows air to pass through while preventing flames from escaping, thereby reducing the likelihood of fire hazards in the engine area.

The other options do not accurately describe the primary function of a backfire flame arrestor. While it can have some effect on engine performance, that is not its main purpose. It is not universally required for all safety scenarios, as its necessity can depend on local regulations and specific engine setups. Additionally, it is not used in all types of engines, as it is specifically designed for gasoline engines that are at risk of backfire. Thus, the correct answer emphasizes the vital safety function that the flame arrestor provides in preventing potentially catastrophic events associated with engine backfires.