What is the minimum temperature required for WAO?

• A. 30‚àö√Ñ‚àö‚àÇC
• B. 50‚àö√Ñ‚àö‚àÇC
• C. 90‚àö√Ñ‚àö‚àÇC
• D. 150‚àö√Ñ‚àö‚àÇC