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: a sum of money at simple interest amounts to rs . 825 in 3 years and to rs . 846 in 4 years . the sum is ? 
Options: a ) s . 738 , b ) s . 638 , c ) s . 650 , d ) s . 762 , e ) s . 735
Example Output: d

Example Input: Problem: in a certain pond , 80 fish were caught , tagged , and returned to the pond . a few days later , 50 fish were caught again , of which 2 were found to have been tagged . if the percent of tagged fish in the second catch approximates the percent of tagged fish in the pond , what is the approximate number of fish in the pond ? 
Options: a ) 400 , b ) 625 , c ) 1,250 , d ) 2,000 , e ) 10,000
Example Output: d

Example Input: Problem: there are 50 students in a class . if 12 % are absent on a particular day , find the number of students present in the class . 
Options: a ) 43 , b ) 36 , c ) 28 , d ) 129 , e ) 44
Example Output:
e