Fully Developed Stage occurs when all combustible materials in the compartment are burning.

• A. No flames present
• B. Only surface flames
• C. All combustible materials in the compartment are burning
• D. Only ignition of small flame

Answer: (C)

Fully developed fire means all combustibles in the compartment are burning. This stage occurs after growth when every fuel source in that space is involved, causing maximum heat release, flames present throughout the area, and extreme conditions that raise the risk of flashover. That’s why the statement describing all combustibles in the compartment burning best captures this stage. If there are no flames, or only surface flames or a small ignition, the fire is in the ignition or growth phases, not fully developed. In practice, recognizing this stage signals the highest danger and the need for rapid, coordinated suppression and safety planning.