What is the definition of combustion?

The correct answer defines combustion as the process of rapid oxidation by which heat stored in fuel is released. This accurately captures the essence of combustion, which typically involves a chemical reaction between a fuel (usually containing carbon and hydrogen) and an oxidizing agent (generally oxygen). During this exothermic reaction, energy is released in the form of heat and light, which is the primary characteristic of combustion.

Understanding this process is crucial in various fields, such as engineering, environmental science, and energy production, and it underlies many practical applications, including engines, heating systems, and power generation. The rapid nature of the oxidation reaction is what distinguishes combustion from other chemical processes that may involve slower oxidation or, in some cases, no oxidation at all.

Other options suggest processes that do not align with the fundamental definition of combustion. For instance, solidifying fuel or refining fuel focuses on altering the state or improving the efficiency of the fuel rather than describing the chemical reaction itself. Cooling fuel to prevent fire pertains to fire prevention strategies and does not address the nature of combustion as a process. Therefore, option B is the only choice that encapsulates both the rapid nature of the reaction and the release of energy characteristic of combustion.