A satellite's orbital period $T$ for a circular orbit around the Earth is related by $T^2 = \frac{k r^3}{M}$, where $r$ is the radius of the orbit, $M$ is the mass of the Earth and $k$ is a constant. What are the SI base units of $k$?
- A$\text{kg}^{-1}\,\text{m}^{-3}\,\text{s}^2$
- B$\text{kg}^{-1}\,\text{m}^3\,\text{s}^2$
- C$\text{kg}\,\text{m}^{-3}\,\text{s}^2$
- D$\text{kg}\,\text{m}^3\,\text{s}^2$