A disc having a uniform charge density $\;\sigma\;$ and radius $\;R\;$ is placed on $\;x-y\;$ plane with centre at the origin . Find the electric potential at a point on z - axis at a distance $\;10 m\;$ from centre . $\;\sigma=16\;\in_{0}\;,R=1 m$

Question

$(a)\;0.1\qquad(b)\;0.4\qquad(c)\;1.6\qquad(d)\;None\;of\;these$