What is required for combustion to occur?

The requirement for combustion primarily involves the presence of fuel, oxygen, and heat. Atomization of fuel is a critical process that prepares the fuel for efficient burning by breaking it into small droplets, which can mix more effectively with oxygen. This maximizes the surface area of the fuel that is exposed to oxygen, facilitating the combustion process. Heat serves to initiate the combustion reaction and sustain it once it has started. Without heat, the fuel-oxygen mixture will not ignite.

The other options lack one or more key components essential for combustion. For instance, water is not a necessary component and can actually inhibit combustion by cooling the fuel and displacing oxygen. Similarly, while electricity is useful for certain ignition systems, it is not a requisite element for the combustion process itself, and pressure alone does not sustain combustion since heat is necessary for the actual reaction to take place.