Which of the following is considered a Class A combustible?

Class A combustibles are materials that can easily ignite and are primarily solid substances. They typically involve ordinary combustibles like wood, paper, cloth, and many plastics. In this case, wood is categorized as a Class A combustible because it is a common organic material that burns readily when exposed to heat or flame.

Magnesium, while it is a combustible metal, falls into a different category due to its chemical properties and behavior when it ignites. Gasoline and rocket fuel are classified as Class B and Class C combustibles, respectively, as they are flammable liquids and gases, which behave differently when ignited compared to solid materials like wood. Hence, wood is the correct representation of a Class A combustible.