A thin plastic disc, which is a quarter of a circle of radius $$R=0.6\ \text{m}$$, lies in the first quadrant of the $$x-y$$ plane, with the center of curvature at the origin $$O$$ as shown. It is charged uniformly on one side with surface charge density $$\sigma$$. Electric potential at point $$P(0,0,0.8\ \text{m})$$ is

A

$$\frac{\sigma}{8\varepsilon_0}$$

B

$$\frac{\sigma}{8\pi\varepsilon_0}$$

C

$$\frac{\sigma}{20\varepsilon_0}$$

D

$$\frac{\sigma}{40\varepsilon_0}$$