option C <B = 54° ( answer is attached )
 
        
                    
             
        
        
        
Assuming S=1 you would take the log of 8.5 and the log of 5.3 and subtract then to get the difference in intensity. If you put that in a calculator you will get roughly 0.205143056
 
        
             
        
        
        
I think A is 145m... 
200m+ (-55m) since the submarine is under water it will be negative which ends up to be 145m