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: marcella has 27 pairs of shoes . if she loses 9 individual shoes , what is the greatest number of matching pairs she could have left ? 
Options: a ) 22 , b ) 20 , c ) 19 , d ) 16 , e ) 15
Example Output: a

Example Input: Problem: ( 0.15 ) ( power 3 ) - ( 0.1 ) ( power 3 ) / ( 0.15 ) ( power 2 ) + 0.015 + ( 0.1 ) ( power 2 ) is : 
Options: a ) 0.68 , b ) 0.08 , c ) 0.05 , d ) 0.06 , e ) none of them
Example Output: c

Example Input: Problem: the largest natural number by which the product of 3 consecutive even natural numbers is always divisible , is 
Options: a ) 16 , b ) 24 , c ) 48 , d ) 96 , e ) 78
Example Output:
c