Consider a function $\overrightarrow{f}=\dfrac{1}{r^{2}} \hat{r}$ where $r$ is the distance from the origin and $\hat{r}$ is the unit vector in the radial direction. The divergence of this function over a sphere of radius $R$, which includes the origin, is
- $0$
- $2 \pi$
- $4 \pi$
- $R \pi$