In this task, you need to answer the given multiple-choice question on the physics. Classify your answers into 'a', 'b', 'c', 'd', and 'e'.

Ex Input:
Problem: how many seconds will a 1200 m long train take to cross a man walking with a speed of 3 km / hr in the direction of the moving train if the speed of the train is 63 km / hr ?
Options: a ) 26 sec , b ) 65 sec , c ) 55 sec , d ) 19 sec , e ) 72 sec

Ex Output:
e

Ex Input:
Problem: the speed at which a man can row a boat in still water is 15 km / hr . if he rows downstream , where the speed of current is 3 km / hr , how many seconds will he take to cover 90 meters ?
Options: a ) 12 , b ) 16 , c ) 17 , d ) 18 , e ) 20

Ex Output:
d

Ex Input:
Problem: a person can swim in still water at 10 km / h . if the speed of water 8 km / h , how many hours will the man take to swim back against the current for 16 km ?
Options: a ) 3 , b ) 7 , c ) 5 , d ) 8 , e ) 6

Ex Output:
d