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'.

Ex 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

Ex Output:
c


Ex Input:
Problem: how many 3 - digit positive integers are there , where each digit is positive , and no 3 adjacent digits are same ? 
Options: a ) 1236 , b ) 504 , c ) 4096 , d ) 4608 , e ) 6561

Ex Output:
b


Ex Input:
Problem: a certain characteristic in a large population has a distribution that is symmetric about the mean m . if 84 percent of the distribution lies within one standard deviation d of the mean , what percent of the distribution is less than m + d ? 
Options: a ) 16 % , b ) 32 % , c ) 48 % , d ) 84 % , e ) 92 %

Ex Output:

e