The electric flux through the surface:

1. in figure-(iv) is the largest
2. in figure-(iii) is the least
3. in figure-(ii) is same as figure-(iii) but is smaller than figure-(iv)
4. is the same for all the figures

Hint: Use Gauss'law.

Step 1: Gauss' law of electrostatics state that the total of the electric flux out of a closed surface is equal to the charge enclosed divided by the permittivity i.e., electric flux =Qε0.

Step 2: Thus, electric flux through a surface does not depend on the shape, size or area of a closed surface but it depends on the number of charges enclosed by the surface.

So, here in this question, all the figures have the same electric flux as all of them has single positive charge.