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: ages of two persons differ by 20 years . if 6 year ago , the elder one be 3 times as old the younger one , find their present age
Options: a ) 12,28 , b ) 14,30 , c ) 16,36 , d ) 18,34 , e ) 19,34

Ex Output:
c

Ex Input:
Problem: the average age of 15 students of a class is 15 years . out of these , the average age of 8 students is 14 years and that of the other 6 students is 16 years , the age of the 15 th student is
Options: a ) 17 , b ) 12 , c ) 13 , d ) 14 , e ) 15

Ex Output:
a

Ex Input:
Problem: the average age of 15 students of a class is 15 years . out of these , the average age of 8 students is 14 years and that of the other 6 students is 16 years , the age of the 15 th student is
Options: a ) 17 , b ) 12 , c ) 13 , d ) 14 , e ) 15

Ex Output:
a