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: jar a has 26 % more marbles than jar b . what percent of marbles from jar a need to be moved into jar b so that both jars have equal marbles ? 
Options: a ) 7.6 % , b ) 8.3 % , c ) 9.6 % , d ) 10.3 % , e ) 11.5 %
Example Output: d

Example Input: Problem: if it is assumed that 60 percent of those who receive a questionnaire by mail will respond and 222 responses are needed , what is the minimum number of questionnaires that should be mailed ? 
Options: a ) 280 , b ) 370 , c ) 460 , d ) 550 , e ) 640
Example Output:
b