Outdoor fires are considered to be _____ due to an unlimited oxygen supply.

Outdoor fires are considered to be fuel-limited due to the abundant and unrestricted supply of oxygen available in an outdoor environment. This means that under typical outdoor conditions, fires are able to access as much oxygen as they need for combustion, which allows them to burn more freely and intensely compared to a confined space with limited air supply.

When discussing fire dynamics, "fuel-limited" refers to scenarios where the amount of fuel determines the fire's growth and intensity, not the amount of oxygen. In outdoor settings, since the oxygen is plentiful and the limitation on fire behavior primarily comes from fuel availability, these fires can exhibit greater rates of combustion and can quickly spread if there is enough combustible material present.

In contrast, in more enclosed environments, fire behavior may be more influenced by ventilation and the availability of oxygen, leading to different classifications such as ventilation-limited fires. Thus, recognizing the outdoor fire as fuel-limited aligns with its characteristics of having unlimited oxygen supply.