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'.

Example Input: Problem: a , b , k start from the same place and travel in the same direction at speeds of 30 km / hr , 40 km / hr , 50 km / hr respectively . b starts two hours after a . if b and k overtake a at the same instant , how many hours after a did k start ? 
Options: a ) 2.4 , b ) 3.2 , c ) 4.0 , d ) 4.8 , e ) 5.6
Example Output: b

Example Input: Problem: a train is 300 meter long is running at a speed of 35 km / hour . in what time will it pass a bridge of 115 meter length ? 
Options: a ) 29 , b ) 23 , c ) 47.119 , d ) 44.586 , e ) 42.686
Example Output: e

Example Input: Problem: a and b together can do a piece of work in 5 days . if a alone can do the same work in 20 days , then b alone can do the same work in ? 
Options: a ) 0.35 days , b ) 0.45 days , c ) 0.55 days , d ) 0.25 days , e ) 0.15 days
Example Output:
e