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: the radius of a circular wheel is 1.75 m , how many revolutions will it make in traveling 1 km ? 
Options: ['a ) 1000', 'b ) 2788', 'c ) 2677', 'd ) 2899', 'e ) 2771']

Ex Output:
a


Ex Input:
Problem: a train 250 m long is running at a speed of 45 km / hr . in what time will it pass a bridge 150 m long ? 
Options: a ) 45 sec , b ) 42 sec , c ) 32 sec , d ) 48 sec , e ) 25 sec

Ex Output:
c


Ex Input:
Problem: if 3 people can do 3 times of a particular work in 3 days , then how many days would it take 4 people to do 4 times of that particular work ? 
Options: a ) 1 , b ) 2 , c ) 3 , d ) 4 , e ) 7

Ex Output:

c