Task: Question Answering
Input (English): Problem: if a certain number of people can dig earth 100 m deep , 25 m long , and 30 m broad in 12 days , then find the number of days the same number of people will require to dig earth 75 m deep , 20 m long and 50 m broad . 
Options: a ) 12 , b ) 18 , c ) 6 , d ) 1 , e ) 17
Output (English): a