What defines an accidental fire?

An accidental fire is characterized by being a fire that occurs without intentional human intervention, meaning it arises from unforeseen circumstances rather than a deliberate act. Essentially, this definition encompasses any situation where the fire is not started purposefully but results from incidents such as electrical malfunctions, cooking accidents, or other unintended sources.

The option indicating that a fire not involving a deliberate human act aligns perfectly with this definition, as it captures the essence of what constitutes an accidental fire. In contrast, other options specify different types of fires: an act of arson refers to deliberately setting a fire with the intent to cause harm, while a fire started by natural causes would be more specific to events like lightning strikes, which are not always classified as accidental in the same broad way. The last option, regarding intentionally controlled fires, describes situations such as controlled burns for land management, which are certainly not accidental. Thus, option C comprehensively and accurately defines an accidental fire.