Potential difference between centre and surface of the sphere of radius R and $\rho$ uniform volume charge density within it will be

Question

$(a)\;\large\frac{\rho R^2}{6 \in_{0}}\qquad(b)\;\large\frac{\rho R^2}{4\in_{0}} \qquad(c)\;\large\frac{\rho R^2}{3 \in_{0}}\qquad(d)\;\large\frac{\rho R^2}{2 \in_{0}}$