- A$\text{p}{_0}^\text{r}\Big(\frac{5}{3}-\frac{\text{r}}{\text{R}}\Big)$
- B$\frac{4\pi\text{p}{_0}^\text{r}}{3\in_0}\Big(\frac{5}{3}-\frac{\text{r}}{\text{R}}\Big)$
- C$\frac{4\text{p}{_0}^\text{r}}{4\in_0}\Big(\frac{5}{4}-\frac{\text{r}}{\text{R}}\Big)$
- D$\frac{\text{p}{_0}^\text{r}}{3\in_0}\Big(\frac{5}{4}-\frac{\text{r}}{\text{R}}\Big)$