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: find the simple interest on rs . 520 for 7 months at 8 paisa per month ? 
Options: a ) 277 , b ) 270 , c ) 291 , d ) 266 , e ) 121
Example Output: c

Example Input: Problem: sheela deposits rs . 4500 in bank savings account . if this is 28 % of her monthly income . what is her monthly income in ? 
Options: a ) 22000 , b ) 27000 , c ) 16071 , d ) 16789 , e ) none of these
Example Output: c

Example Input: Problem: at what rate percent per annum will a sum of money double in 6 years . 
Options: a ) 12.5 % , b ) 13.5 % , c ) 11.5 % , d ) 14.5 % , e ) 16.6 %
Example Output:
e