Task: Question Answering
Input (English): Problem: a and b invests rs . 2000 and rs . 4000 respectively in a business . if a doubles his capital after 6 months . in what ratio should a and b divide that year ' s profit ? 
Options: a ) 3 : 5 , b ) 3 : 4 , c ) 9 : 2 , d ) 9 : 9 , e ) 3 : 1
Output (English): b