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 distance between 2 cities a and b is 1000 km . a train starts from a at 11 a . m . and travels towards b at 100 km / hr . another starts from b at 12 p . m . and travels towards a at 150 km / hr . at what time do they meet ? 
Options: a ) 11 am . , b ) 12 p . m . , c ) 3 pm . , d ) 4 p . m . , e ) 1 p . m .
Example Output: d

Example Input: Problem: if a train , travelling at a speed of 360 kmph , crosses a pole in 5 sec , then the length of train is ? 
Options: a ) 381 m , b ) 112 m , c ) 500 m , d ) 125 m , e ) 433 m
Example Output: c

Example Input: Problem: gary drove from point a to point b at 60 km / h . on his way back he took a train travelling at 110 km / h and therefore his trip back lasted 5 hours less . what is the distance ( in km ) between a and b ? 
Options: a ) 600 . , b ) 630 . , c ) 660 . , d ) 690 . , e ) 720 .
Example Output:
c