Electric charges and fields chapter..

Answer is 2nd option.

Explain it...

Net flux = flux of curved surface + flux of plane

Flux through plane = E*pi*r^2*cos 180 = - E*pi*r^2

Since the angle is 180 because direction of field lines is opposite to direction of area vector of plane surface. The field lines are in the direction of area vector of curved surface, that is , the hemispherical part or curved part.

 

Now flux through  curved surface area = 2E*pi*r²

Net flux  = 2E*pi*r²+ (- E*pi*r²) = E*pi*r².

Hence option (B) is the answer.