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: if a person walks at 20 km / hr instead of 10 km / hr , he would have walked 20 km more . the actual distance traveled by him is : 
Options: a ) 20 km , b ) 56 km , c ) 60 km , d ) 70 km , e ) 80 km
Example Output: a

Example 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
Example Output: a

Example Input: Problem: the average age of 15 students of a class is 15 years . out of these , the average age of 6 students is 14 years and that of the other 9 students is 16 years , the age of the 15 th student is 
Options: a ) 11 , b ) 12 , c ) 13 , d ) 14 , e ) 15
Example Output:
c