What is produced as a result of combustion?

The correct answer reflects that combustion is a chemical reaction that occurs when a fuel reacts with an oxidant, usually oxygen, resulting in the release of energy. During this process, heat and light energy are produced as byproducts, making it an exothermic reaction.

When a fuel burns completely, the primary products of this reaction typically include carbon dioxide and water vapor; however, the significant focus in this context is on the heat and light generated. This energy release is what makes combustion useful in various applications, such as in engines, heating systems, and cooking.

The other options incorrectly simplify or misrepresent the products of combustion. For example, stating that only carbon dioxide is produced ignores the essential heat and light energy generation fundamental to combustion. Similarly, identifying only water vapor as a product fails to encompass the full scope of combustion's outcomes. Lastly, unburned fuel would suggest incomplete combustion, which does occur but is not a direct product of the combustion process itself. Thus, heat and light energy represent the core essence of what is produced as a result of combustion, confirming the correctness of the chosen answer.