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: what sum of money will produce rs . 70 as simple interest in 4 years at 4 1 / 2 percent ? 
Options: a ) 263 , b ) 500 , c ) 388.9 , d ) 368 , e ) 339
Example Output: c

Example Input: Problem: 30 is what percent of 100 ? 
Options: a ) 35 % , b ) 30 % , c ) 45 % , d ) 50 % , e ) 55 %
Example Output: b

Example Input: Problem: a library branch originally contained 18365 volumes , 30 % of which were fiction novels . 1 / 3 of the volumes were transferred to another location and 1 / 3 of the volumes transferred were fiction novels . what percent of the remaining collection was fiction novels ? 
Options: a ) 2.5 % , b ) 17.67 % , c ) 28.3 % , d ) 45.2 % , e ) 73.6 %
Example Output:
c