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'.

Input: Consider Input: Problem: a train is 485 meter long is running at a speed of 45 km / hour . in what time will it pass a bridge of 140 meter length 
Options: a ) 20 seconds , b ) 30 seconds , c ) 40 seconds , d ) 50 seconds , e ) none of these

Output: d


Input: Consider Input: Problem: a 180 meter long train crosses a man standing on the platform in 9 sec . what is the speed of the train ? 
Options: a ) 72 , b ) 108 , c ) 1266 , d ) 188 , e ) 211

Output: a


Input: Consider Input: Problem: noelle walks from point a to point b at an average speed of 3 kilometers per hour . at what speed , in kilometers per hour , must noelle walk from point b to point a so that her average speed for the entire trip is 4 kilometers per hour ? 
Options: a ) 5.75 , b ) 6 , c ) 7.25 , d ) 7.5 , e ) 7.75


Output: b