During which process is energy produced as heat and light?

Combustion is the correct answer because it is a chemical process that involves the rapid reaction of a fuel with an oxidizer, typically oxygen, producing energy in the form of both heat and light. This exothermic reaction not only generates significant amounts of energy but also leads to the formation of byproducts such as carbon dioxide and water vapor.

In the context of fire investigations as outlined in NFPA 921, understanding combustion is critical because it helps investigators analyze how fires initiate and spread. Combustion is fundamental in generating the heat necessary to sustain a fire and can produce visible flames and incandescent materials, which are manifestations of released energy.

The other processes listed—conduction, convection, and radiation—are forms of heat transfer rather than chemical reactions that create energy. Conduction refers to heat transfer through direct contact, convection involves the movement of heat through fluids, and radiation is the transfer of heat through electromagnetic waves. While these processes are important for understanding thermal dynamics in fire scenarios, they do not produce energy; rather, they describe how energy is transferred once it has been created, typically through combustion.