Task: Question Answering
Input (English): Problem: a rower whose speed is 4 km / hr in still water rows to a certain point upstream and back to the starting point in a river which flows at 2 km / hr . what is the rower ' s average speed ( in km / hr ) for the total journey ? 
Options: a ) 6 , b ) 4 , c ) 9 , d ) 3 , e ) 2
Output (English): d