What is the best choice for the shape of a gaussian surface?

a) spherical

b) cylindrical

c) cubic

d) it should be one that encloses the smallest volume.

e) it should be one that matches the symmetry of the charge distribution.

It should be one that matches the symmetry of the charge distribution

Explanation: Gaussian surfaces are usually carefully chosen to exploit symmetries of a situation to simplify the calculation of the surface integral. If the Gaussian surface is chosen such that for every point on the surface the component of the electric field along the normal vector is constant, then the calculation will not require difficult integration as the constants which arise can be taken out of the integral.It is defined as the closed surface in three dimensional space by which the flux of vector field be calculated.

force tends to be low and long diustance masses are high

force required to detach it is given by

charges are taken to be fundamental charge

now we have

so above is the minimum distance at which it will detach