Which of the following is NOT considered a solid fuel that can support combustion?

The choice of water as the correct answer is based on its fundamental properties in relation to combustion. Water is a compound made of hydrogen and oxygen and is known for its ability to extinguish fires rather than support them. It does not have the characteristics necessary to support combustion because it does not produce flammable vapors or sustain a chemical reaction that releases energy in the form of heat and light when combined with an oxidizer, such as oxygen.

In contrast, wood, coal, and magnesium are all materials that have the capacity to burn, serving as fuels that can initiate and sustain combustion. Wood provides a carbon-based structure, coal is a carbon-rich mineral that ignites at high temperatures, and magnesium is a metal that can ignite in the presence of oxygen due to its high reactivity and can burn with a bright white flame. Thus, the distinction lies in the unique properties of water as a non-combustible substance, differentiating it from the other solid fuels mentioned.