A boat which has a speed of 5 km/h in still water crosses a river of width 1 km along the shorter possible path in 15 min. Find the component of resultant velocity of swimmers in perpendicular direction to river flow

Question

$\begin{array}{1 1} (a) \;1 \\ (b) \;3\\ (c) \;4\\ (d) \;5\end{array} $