What is the divergence of the field F=r∥r∥3\mathbf{F} = \frac{\mathbf{r}}{\|\mathbf{r}\|^3}F=∥r∥3r where r=⟨x,y,z⟩\mathbf{r} = \langle x, y, z \rangler=⟨x,y,z⟩ for r≠0\mathbf{r} \neq 0r=0?
111
333
000
1/r1/r1/r