The mass density of a spherical galaxy varies as $$\frac{K}{r}$$ over a large distance $$r$$ from its center. In that region, a small star is in a circular orbit of radius R. Then the period of revolution, T depends on R as:

A

$$T^2 \propto R$$

B

$$T^2 \propto R^3$$

C

$$T^2 \propto \frac{1}{R^3}$$

D

$$T \propto R$$