For a vehicle travelling at speed $v$, the stopping distance $d$ after the brakes are applied is given by $d = kv^2$, where $k$ is a constant. State the unit of $k$ written in SI base units.
- A$\text{m}^{-1}\text{s}^2$
- B$\text{m s}^{-2}$
- C$\text{m}^2\text{s}^{-2}$
- D$\text{m}^{-1}\text{s}$