Cold air is correct answer
        
                    
             
        
        
        
Answer:
The electromagnetic radiation per-unit- area increase by 42.65 times.
Explanation:
The radiation per-unit- area (P) is directly proportional to the fourth power of the temperature. Thus, 
P ∝ T⁴ 
For, when the temperature is raised from T₀ to T₁ , the radiation per-unit- area is related to as:

T₀ =  900 K
T₁ = 2300 K

So, 
<u>P₁ = 42.65 P₀</u>
<u>The electromagnetic radiation per-unit- area increase by 42.65 times.</u>