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: after decreasing 40 % in the price of an article costs rs . 1050 . find the actual cost of an article ? 
Options: a ) 1200 , b ) 1750 , c ) 1050 , d ) 1570 , e ) 1005
Example Output: b

Example Input: Problem: one night 17 percent of the female officers on a police force were on duty . if 170 police officers were on duty that night and half of these were female officers , how many female officers were on the police force ? 
Options: a ) 400 , b ) 420 , c ) 450 , d ) 480 , e ) 500
Example Output: e

Example Input: Problem: the population of a town is 7900 . it decreases annually at the rate of 10 % p . a . what was its population 2 years ago ? 
Options: a ) 9750 , b ) 8000 , c ) 8500 , d ) 9500 , e ) 10000
Example Output:
a