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: a swimmer can swim in still water at 4 km / h . if the speed of the water current is 2 km / h , how many hours will the swimmer take to swim against the current for 5 km ? 
Options: a ) 2.0 , b ) 2.5 , c ) 3.0 , d ) 3.5 , e ) 4.0

Ex Output:
b


Ex Input:
Problem: the speed of a car is 60 km in the first hour and 30 km in the second hour . what is the average speed of the car ? 
Options: a ) 45 kmph , b ) 65 kmph , c ) 75 kmph , d ) 85 kmph , e ) 90 kmph

Ex Output:
a


Ex Input:
Problem: a man rows his boat 78 km downstream and 56 km upstream , taking 4 hours each time . find the speed of the stream ? 
Options: a ) 6 , b ) 5 , c ) 7 , d ) 8 , e ) 3

Ex Output:

e