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 rower whose speed is 2.5 km / hr in still water rows to a certain point upstream and back to the starting point in a river which flows at 0.5 km / hr . what is the rower ' s average speed ( in km / hr ) for the total journey ? 
Options: a ) 2.2 , b ) 2.3 , c ) 2.4 , d ) 2.5 , e ) 2.6

Ex Output:
c


Ex Input:
Problem: the average of 5 numbers is 27 . if one number is excluded the average become 25 . the excluded number is : 
Options: a ) 25 , b ) 27 , c ) 30 , d ) 35 , e ) 37

Ex Output:
d


Ex Input:
Problem: in a group of cows and chickens , the number of legs was 18 more than twice the number of heads . the number of cows was : 
Options: a ) 5 , b ) 7 , c ) 9 , d ) 12 , e ) 14

Ex Output:

c