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'.

Ex 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

Ex Output:
d


Ex Input:
Problem: the population of a town is 10000 . it increases annually at the rate of 20 % p . a . what will be its population after 1 year ? 
Options: a ) 12300 , b ) 12350 , c ) 12000 , d ) 12500 , e ) 12600

Ex Output:
c


Ex Input:
Problem: if the cost price of 12 pencils is equal to the selling price of 8 pencils , the gain percent is : 
Options: a ) 30 , b ) 40 , c ) 50 , d ) 60 , e ) 70

Ex Output:

c