In this task, you need to answer the given multiple-choice question on the gain. Gain is the value by which to multiply the input. Classify your answers into 'a', 'b', 'c', 'd', and 'e'.

Example Input: Problem: 90 students represent x percent of the boys at jones elementary school . if the boys at jones elementary make up 50 % of the total school population of x students , what is x ? 
Options: a ) 134 , b ) 150 , c ) 225 , d ) 250 , e ) 500
Example Output: a

Example Input: Problem: the interest on a certain deposit at 4.5 % p . a . is rs . 405 in one year . how much will the additional interest in one year be on the same deposit at 5 % p . a . ? 
Options: a ) rs . 50 , b ) rs . 45 , c ) rs . 40.5 , d ) rs . 48.5 , e ) rs . 49.5
Example Output: b

Example Input: Problem: a reduction of 25 % in the price of apples would enable a man to obtain 36 more for rs . 25 , what is reduced price per dozen ? 
Options: a ) 2 , b ) 3 , c ) 6 , d ) 7 , e ) 10
Example Output:
a