Which term refers to the rapid spread of flames and heat through buildings?

The correct answer is flashover. Flashover is a critical phenomenon in firefighting that occurs when all combustible materials in a room or space reach their ignition temperature simultaneously, resulting in a sudden and rapid spread of flames. This event significantly increases the heat and fire intensity, making it extremely dangerous for both occupants and firefighters.

Flashover typically happens in enclosed spaces where the heat generated by the fire can build up, causing the temperatures to rise enough for the materials present to ignite all at once. Understanding this term is crucial for firefighters as it helps them recognize the signs of imminent flashover, enabling them to take measures to protect themselves and potentially alter their firefighting strategies.

The other options describe different fire-related concepts. Backdraft refers to an explosive event caused by the sudden influx of air into an oxygen-depleted environment, leading to a rapid combustion. Combustion is simply the chemical process of burning, while smoldering describes the slow, low-temperature burning process that occurs without flames. Each of these terms is important in the context of fire behavior and firefighting tactics but does not describe the rapid spread of flames and heat through buildings as precisely as flashover does.