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 can do a piece of work in 80 days and b in 100 days . they work together for 20 days and then b goes away . in how many days will a finish the remaining work ? 
Options: a ) 33 days , b ) 44 days , c ) 55 days , d ) 42 days , e ) 32 days
Example Output: b

Example Input: Problem: an engine moves at the speed of 60 kmph without any coaches attached to it . speed of the train reduces at the rate that varies directly as the square root of the number of coaches attached . when 4 coaches are attached speed decreases to 48 kmph . what will be the speed of train when 36 coaches are attached . 
Options: a ) 24 , b ) 28 , c ) 20 , d ) 32 , e ) 40
Example Output: a

Example Input: Problem: a boat running upstream takes 8 hours 48 minutes to cover a certain distance , while it take 4 hours to cover the same distance running downstream . what is the ratio between the speed of the boat and speed of the water current respectively ? 
Options: a ) 1 : 3 , b ) 3 : 8 , c ) 6 : 3 , d ) 8 : 3 , e ) none
Example Output:
d