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 train 300 m long takes 9 sec to cross a man walking at 3 kmph in a direction opposite to that of the train . find the speed of the train ? 
Options: a ) 100 kmph , b ) 90 kmph , c ) 120 kmph , d ) 117 kmph , e ) 125 kmph
Example Output: d

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: if one length of a square is tripled , and the original parameter is 4 y . what is the new length of one of the sides ? 
Options: ['a ) 12 y / 3', 'b ) 2 y / 2', 'c ) 6 y / 3', 'd ) 12 y / 4', 'e ) 4 y / 3']
Example Output:
d