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: two trains of length 100 meters and 200 meters are 840 meters apart . they are moving towards each other on parallel tracks , at speeds of 54 km / h and 72 km / h . after how many seconds will the trains meet ? 
Options: a ) 20 , b ) 22 , c ) 24 , d ) 26 , e ) 28

Output: c


Input: Consider Input: Problem: excluding stoppages , the speed of a train is 30 kmph and including stoppages it is 21 kmph . of how many minutes does the train stop per hour ? 
Options: a ) 16 , b ) 17 , c ) 12 , d ) 15 , e ) 18

Output: e


Input: Consider Input: Problem: a can do a piece of work in 8 days . b can do it in 16 days . with the assistance of c they completed the work in 4 days . find in how many days can c alone do it ? 
Options: a ) 87 days , b ) 20 days , c ) 26 days , d ) 19 days , e ) 16 days


Output: e