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: two trains of equal length , running with the speeds of 60 and 90 kmph , take 50 seconds to cross each other while they are running in the same direction . what time will they take to cross each other if they are running in opposite directions ? 
Options: a ) 3.2 , b ) 2.6 , c ) 6.6 , d ) 32.2 , e ) 42.2
Example Output: c

Example Input: Problem: a train passes a station platform in 35 sec and a man standing on the platform in 20 sec . if the speed of the train is 54 km / hr . what is the length of the platform ? 
Options: a ) 228 , b ) 240 , c ) 225 , d ) 166 , e ) 1811
Example Output: c

Example Input: Problem: the h . c . f . of two numbers is 12 and their l . c . m . is 600 . if one of the number is 12 , find the other ? 
Options: a ) 100 , b ) 600 , c ) 120 , d ) 200 , e ) 150
Example Output:
b