Task: Question Answering
Input (English): Problem: the time taken by a man to row his boat upstream is twice the time taken by him to row the same distance downstream . if the speed of the boat in still water is 57 kmph , find the speed of the stream ? 
Options: a ) 15 , b ) 17 , c ) 19 , d ) 18 , e ) 16
Output (English): c