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: if x : y = 3 : 5 , find the value of ( 2 x + 4 y ) : ( 3 x – y ) 
Options: a ) 13 : 2 , b ) 11 : 2 , c ) 13 : 3 , d ) 13 : 4 , e ) 13 : 5

Ex Output:
a


Ex Input:
Problem: if a = 1 , what is the value of – ( a ^ 2 + a ^ 3 + a ^ 4 + a ^ 5 ) ? 
Options: a ) - 14 , b ) - 4 , c ) 0 , d ) 4 , e ) 14

Ex Output:

b