Which factor generally increases the complexity of fire behavior?

The presence of unburned fuels significantly increases the complexity of fire behavior because unburned fuels can create unpredictable fire conditions. These fuels include combustible materials that have not yet ignited and are readily available for combustion. When unburned fuels are present, they can lead to rapid fire spread and varying intensity, as they can ignite at different times and intensities, potentially creating complex fire patterns and behaviors.

Additionally, unburned fuels may also contribute to changes in the fire's intensity due to variations in fuel types, moisture content, and density. This adds layers of difficulty in predicting fire movement and behavior, complicating firefighting efforts. In contrast, factors such as stable weather patterns, access to water sources, and uniform terrain generally lead to more predictable and manageable fire conditions, reducing complexity.