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: a father said his son , ` ` i was as old as you are at present at the time of your birth . ` ` if the father age is 32 now , the son age 5 years back was 
Options: a ) 11 , b ) 17 , c ) 11 , d ) 19 , e ) 99

Ex Output:
a


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: 365 : 90 : : 623 : ? 
Options: a ) 36 , b ) 45 , c ) 123 , d ) 63 , e ) none of these

Ex Output:

a