A parallel plate capacitor is made of two circular plates separated by a distance of $5 \mathrm{~mm}$ and with a dielectric constant of $2.2$ between them. When the electric field in the dielectric is $3 \times 10^{4} \mathrm{~V} / \mathrm{m}$, the charge density of the positive plate will be close to
(A) $6 \times 10^{-7} \mathrm{C} / \mathrm{m}^{2}$
(B) $3 \times 10^{-7} \mathrm{C} / \mathrm{m}^{2}$
(C) $3 \times 10^{4} \mathrm{C} / \mathrm{m}^{2}$
(D) $6 \times 10^{4} \mathrm{C} / \mathrm{m}^{2}$