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: the unit digit in the product ( 784 x 618 x 917 x 463 ) is : 
Options: a ) 5 , b ) 9 , c ) 16 , d ) 2 , e ) 42
Example Output: d

Example Input: Problem: of the 13 employees in a certain department , 1 has an annual salary of 38,000 , 2 have an annual salary of 45,700 each , 2 have an annual salary of 42,500 each , 3 have an annual salary of 40,000 each and 5 have an annual salary of 48,500 each . what is the median annual salary for the 13 employees ? 
Options: a ) 38,000 , b ) 40,000 , c ) 42,500 , d ) 45,700 , e ) 48,500
Example Output: d

Example Input: Problem: marcella has 20 pairs of shoes . if she loses 9 individual shoes , what is the greatest number of matching pairs she could have left ? 
Options: a ) 21 , b ) 20 , c ) 19 , d ) 16 , e ) 15
Example Output:
e