A bus is moving with a speed of `10 ms^-1` on a straight road. A scooterist wishes to overtake the bus in `10 s`. If the bus is at a distance of `1 km` from the scooterist with what speed should the scooterist chase the bus ?
A. `10 m s^(-1)`
B. `20 m s^(-1)`
C. `50 m s^(-1)`
D. `30 m s^(-1)`