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'.

Input: Consider Input: Problem: a and b can do a piece of work in 8 days . with the help of c they finish the work in 4 days . c alone can do that piece of work in ? 
Options: a ) 40 days , b ) 20 days , c ) 8 days , d ) 60 days , e ) 40 days

Output: c


Input: Consider Input: Problem: a train 100 m long can cross an electric pole in 20 sec and then find the speed of the train ? 
Options: a ) 19 kmph , b ) 18 kmph , c ) 72 kmph , d ) 17 kmph , e ) 91 kmph

Output: b


Input: Consider Input: Problem: a train covers a distance of 18 km in 10 min . if it takes 6 sec to pass a telegraph post , then the length of the train is ? 
Options: a ) 177 , b ) 168 , c ) 120 , d ) 882 , e ) 180


Output: e