A point charge Q is located on the axis of a disc is radius R at a distance b from the plane of the disc . Find the electric flux through the disc if R= $\;\sqrt{3}\;b$

Question

$(a)\;\large\frac{Q}{4\;\in_{0}}\qquad(b)\;\large\frac{Q}{2\;\in_{0}}\qquad(c)\;\large\frac{Q}{3\;\in_{0}}\qquad(d)\;\large\frac{Q}{8\;\in_{0}}$