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 bicycle wheel has a diameter of 0.51 m . how many complete revolutions does it make in 1 km ?
Options: a ) 246 , b ) 448 , c ) 1408 , d ) 710 , e ) 624
Example Output: e

Example Input: Problem: a train 180 m long is running with a speed of 55 km / hr . in what time will it pass a man who is running at 7 km / hr in the direction opposite to that in which the train is going ?
Options: a ) 5.5 , b ) 10.45 , c ) 7 , d ) 8 , e ) 9.5
Example Output: b

Example Input: Problem: a can finish a work in 12 days and b can do the same work in 15 days . b worked for 10 days and left the job . in how many days , a alone can finish the remaining work ?
Options: a ) 4 , b ) 5 1 / 2 , c ) 6 , d ) 8 , e ) none of these
Example Output:
a