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 284 m in length crosses a telegraph post in 18 seconds . the speed of the train is ? 
Options: a ) 77 kmph , b ) 55 kmph , c ) 57 kmph , d ) 58 kmph , e ) 76 kmph
Example Output: c

Example Input: Problem: an employer pays rs . 20 for each day a worker works and for felts rs . 3 for each day is ideal at the end of sixty days a worker gets rs . 280 . for how many days did the worker remain ideal ? 
Options: a ) 10 , b ) 40 , c ) 30 , d ) 20 , e ) 50
Example Output: b

Example Input: Problem: a group of men decided to do a work in 40 days , but 5 of them became absent . if the rest of the group did the work in 60 days , find the original number of men ? 
Options: a ) 60 , b ) 15 , c ) 40 , d ) 10 , e ) 25
Example Output:
b