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: what is the length of a bridge ( in meters ) , which a train 156 meters long and travelling at 45 km / h can cross in 30 seconds ? 
Options: a ) 203 , b ) 211 , c ) 219 , d ) 227 , e ) 235
Example Output: c

Example Input: Problem: a train 110 m long is running with a speed of 24 km / hr . in what time will it pass a man who is running at 6 km / hr in the direction opposite to that in which the train is going ? 
Options: a ) 7 sec , b ) 6 sec , c ) 8 sec , d ) 14 sec , e ) 13.2 sec
Example Output: e

Example Input: Problem: the length of a train and that of a platform are equal . if with a speed of 90 kmph the train crosses the platform in one minute , then the length of the train in metres is 
Options: a ) 500 , b ) 600 , c ) 750 , d ) 900 , e ) 950
Example Output:
d