0.02Nm²/C
3.14Nm²/C
0.005Nm²/C
0.125Nm²/C
Answer is A.
We know that, Φ = E.A Cos θ. Since the surface area is parallel to the Y-Z plane, therefore, the y component of the electric field will not contribute to the flux through the circular surface.
So, Φ = πr²E₀ = 3.14 × 0.0004 × 100 = 0.125 Nm²/C