Task: Question Answering
Input (English): Problem: at the end of the month , a certain ocean desalination plant ’ s reservoir contained 40 million gallons of water . this amount is one fifth of the normal level . if this amount represents 80 % of the reservoir ’ s total capacity , how many million gallons short of total capacity is the normal level ? 
Options: a ) 20 , b ) 30 , c ) 40 , d ) 50 , e ) 60
Output (English): c