In this task, you need to answer the given multiple-choice question on the general math. Classify your answers into 'a', 'b', 'c', 'd', and 'e'.

Example Input: Problem: what least no . must be subtracted from 50248 so that remaining no . is divisible by 20 ? 
Options: a ) 3 , b ) 2 , c ) 4 , d ) 8 , e ) 6
Example Output: d

Example Input: Problem: in n is a positive integer less than 200 , and 18 n / 60 is an integer , then n has how many different positive prime factors ? 
Options: a ) 2 , b ) 3 , c ) 5 , d ) 6 , e ) 8
Example Output: a

Example Input: Problem: average of money that group of 4 friends pay for rent each month is $ 800 . after one persons rent is increased by 20 % the new mean is $ 880 . what was original rent of friend whose rent is increased ? 
Options: a ) 800 , b ) 900 , c ) 1600 , d ) 1100 , e ) 1200
Example Output:
c