Which of the following is NOT a component of the fire triangle?

The correct choice identifies "Ignition source" as not being a component of the fire triangle. The fire triangle is a model used to understand the necessary components for combustion to occur, which consists of three elements: fuel, heat, and oxygen.

In this model, fuel refers to any combustible material that can catch fire, such as wood, paper, or gasoline. Heat is the energy source that raises the material to its ignition temperature, while oxygen is the element that supports the chemical reaction of combustion. All three components must be present for a fire to ignite and sustain itself.

An ignition source itself is not a standalone component of the fire triangle but rather a process or element that provides the necessary heat to initiate combustion, indicating that it is part of the broader context of fire behavior rather than a basic component of the fire triangle. Understanding this distinction helps in fire prevention strategies, where one might seek to eliminate one of the triangle's components to prevent fire.