( A ) $\frac{\rho_0 r}{4 \varepsilon_0}(\frac{5}{3} - \frac{r}{R})$
( B ) $\frac{\rho_0 r}{3 \varepsilon_0}(\frac{5}{4} - \frac{r}{R})$
( C ) $\frac{4 \pi \rho_0 r}{3 \varepsilon_0}(\frac{5}{3} - \frac{r}{R})$
( D ) $\frac{4 \pi \rho_0 r}{3 \varepsilon_0}(\frac{5}{4} - \frac{r}{R})$