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: if a lends rs . 2000 to b at 10 % per annum and b lends the same sum to c at 11.5 % per annum then the gain of b in a period of 3 years is ? 
Options: a ) 90 , b ) 122.5 , c ) 132.5 , d ) 114.5 , e ) 212.5
Example Output: a

Example Input: Problem: rs 3600 is divided into two parts such that one part is put out at 3 % and the other at 5 % . if the annual interest earned from both the investments be rs 144 , find the first part . 
Options: a ) s 4000 , b ) s 2800 , c ) s 1800 , d ) s 3500 , e ) s 3100
Example Output: c

Example Input: Problem: a sum of 14,800 amounts to 19,800 in 3 years at the rate of simple interest . what is the rate of interest ? 
Options: a ) 12 % , b ) 11 % , c ) 16 % , d ) 15 % , e ) 18 %
Example Output:
b