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 population of a bacteria culture doubles every 2 minutes . approximately how many minutes will it take for the population to grow from 1,000 to 100,000 bacteria 
Options: a ) 10 , b ) 12 , c ) 14 , d ) 16 , e ) 18
Example Output: c

Example Input: Problem: the average of 5 quantities is 9 . the average of 3 of them is 4 . what is the average of remaining 2 numbers ? 
Options: a ) 16.5 , b ) 10 , c ) 8 , d ) 9.5 , e ) none of these
Example Output: a

Example Input: Problem: the average of first 12 natural numbers is ? 
Options: a ) 5.2 , b ) 6.5 , c ) 5.3 , d ) 5.9 , e ) 5.1
Example Output:
b