The conditions depend on the density level of the snow. 
Another reason is the imperfect data gathering especially if initial results are only gathered. 
The third reason is that computer models still find it difficult to see small scale phenomena. 
 
        
             
        
        
        
I believe that the answer to this question is, that laws can be made to prevent certain things/ amounts of things to be used up.
        
                    
             
        
        
        
Answer:
As I think the answer is D.