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 numbers from 19 to 79 are exactly divisible by 11 ? 
Options: a ) 5 , b ) 6 , c ) 9 , d ) 11 , e ) 12
Example Output: b

Example Input: Problem: set s contains exactly 10 numbers and has an average ( arithmetic mean ) of 6.2 . if one of the numbers in set s is increased by 8 , while all other numbers remain the same , what is the new average of set s ? 
Options: a ) 6.6 , b ) 6.7 , c ) 6.8 , d ) 7.0 , e ) 6.9
Example Output: d

Example Input: Problem: in a theater , the first row has 15 seats and each row has 2 more seats than previous row . if the last row has 53 seats , what is the total number of seats in the theater ? 
Options: a ) 600 , b ) 640 , c ) 680 , d ) 720 , e ) 760
Example Output:
c