d
$1$ stat $\mathrm{volt}$ $=300$ $\mathrm{volt}$
$\frac{\mathrm{Q}}{\mathrm{R}}=\frac{\mathrm{Q}}{10}=1$ or $\quad \mathrm{Q}=10$ stat coulomb
$\sigma=\frac{\mathrm{Q}}{4 \pi \mathrm{R}^{2}}=\frac{10}{4 \pi(10)^{2}}=\frac{1}{40 \pi}=8 \times 10^{-3} \mathrm{\,CGS}$ $\mathrm{esu}$