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: two cars , car 1 and car 2 move towards each other from e and y respectively with respective speeds of 20 m / s and 15 m / s . after meeting each other car 1 reaches y in 10 seconds . in how many seconds does car 2 reach e starting from y ?
Options: a ) 15.5 sec , b ) 8.4 sec , c ) 33.6 sec , d ) 31.11 sec , e ) 16.8 sec
Example Output: d

Example Input: Problem: a train running at the speed of 60 km / hr crosses a pole in 30 sec . what is the length of the train ?
Options: a ) 535 m , b ) 178 m , c ) 186 m , d ) 168 m , e ) 500 m
Example Output:
e