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: the length of the bridge , which a train 130 metres long and travelling at 108 km / hr can cross in 30 seconds , is : 
Options: a ) 200 m , b ) 225 m , c ) 245 m , d ) 170 m , e ) 240 m
Example Output: d

Example Input: Problem: two trains of equal length are running on parallel lines in the same direction at 46 km / hr and 36 km / hr . the faster train passes the slower train in 27 seconds . what is the length of each train ( in meters ) ? 
Options: a ) 50.5 , b ) 88.5 , c ) 37.5 , d ) 55.5 , e ) 23.5
Example Output: c

Example Input: Problem: two trains 160 m and 160 m long run at the speed of 60 km / hr and 40 km / hr respectively in opposite directions on parallel tracks . the time which they take to cross each other is ? 
Options: a ) 10.52 sec , b ) 18.8 sec , c ) 14.52 sec , d ) 10.8 sec , e ) 11.52 sec
Example Output:
e