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 man can row upstream at 15 kmph and downstream at 25 kmph , and then find the speed of the man in still water ? 
Options: a ) 27 , b ) 29 , c ) 30 , d ) 20 , e ) 24

Output: d


Input: Consider Input: Problem: two trains of equal lengths take 10 sec and 8 sec respectively to cross a telegraph post . if the length of each train be 120 m , in what time will they cross other travelling in opposite direction ? 
Options: a ) 22 , b ) 12 , c ) 9 , d ) 99 , e ) 21

Output: c


Input: Consider Input: Problem: a work which could be finished in 10 days was finished 3 days earlier after 10 more men joined . the number of men employed was ? 
Options: a ) 15 , b ) 20 , c ) 88 , d ) 71 , e ) 11


Output: a