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 man cycling along the road noticed that every 18 minutes a bus overtakes him and every 6 minutes he meets an oncoming bus . if all buses and the cyclist move at a constant speed , what is the time interval between consecutive buses ? 
Options: a ) 5 minutes , b ) 6 minutes , c ) 8 minutes , d ) 9 minutes , e ) 10 minutes
Example Output: d

Example Input: Problem: the radius of the wheel of a bus is 70 cms and the speed of the bus is 66 km / h , then the r . p . m . ( revolutions per minutes ) of the wheel is 
Options: a ) 200 , b ) 250 , c ) 300 , d ) 330 , e ) none of these
Example Output: b

Example Input: Problem: a train 360 m long is running at a speed of 45 km / hr . in what time will it pass a bridge 165 m long ? 
Options: a ) 40 , b ) 99 , c ) 88 , d ) 77 , e ) 42
Example Output:
e