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: thirty percent of the members of a swim club have passed the lifesaving test . among the members who have not passed the test , 26 have taken the preparatory course and 65 have not taken the course . how many members are there in the swim club ? 
Options: a ) 60 , b ) 80 , c ) 100 , d ) 130 , e ) 140
Example Output: d

Example Input: Problem: sam invested $ 1000 @ 20 % per annum for one year . if the interest is compounded half yearly , then the amount received by sam at the end of the year will be ? 
Options: a ) $ 1542 , b ) $ 1145 , c ) $ 1210 , d ) $ 1642 , e ) $ 1020
Example Output: c

Example Input: Problem: shop offered 32 % offer for every shirt , smith bought a shirt at rs . 650 . and what was the shop ' s original selling price ? 
Options: a ) 955 , b ) 550 , c ) 600 , d ) 700 , e ) 750
Example Output:
a