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: how many odd 3 - digit integers greater than 800 are there such that all their digits are different ? 
Options: a ) 40 , b ) 56 , c ) 72 , d ) 81 , e ) 104
Example Output: c

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: the product of two positive integers is 675 and their difference is 2 . what is the bigger number ? 
Options: a ) 21 , b ) 23 , c ) 25 , d ) 27 , e ) 29
Example Output:
d