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: 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: train a leaves the station traveling at 30 miles per hour . two hours later train в leaves the same station traveling in the same direction at 36 miles per hour . how many miles from the station was train a overtaken by train b ? 
Options: a ) 320 , b ) 360 , c ) 400 , d ) 440 , e ) 480
Example Output: b

Example Input: Problem: it was calculated that 75 men could complete a piece of work in 30 days . when work was scheduled to commence , it was found necessary to send 25 men to another project . how much longer will it take to complete the work ? 
Options: a ) 20 days . , b ) 30 days . , c ) 25 days . , d ) 28 days . , e ) 45 days .
Example Output:
e