Given the task definition and input, reply with output. 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'.

Problem: a man can row 7 a kmph in still water . if in a river running at 1.5 km / hr an hour , it takes him 50 minutes to row to a place and back , how far off is the place ?
Options: a ) 4 km , b ) 2 km , c ) 5 km , d ) 3 km , e ) 1 km
d