In gauss's law, to what does qencl refer?

The choices are as follows:

a) the net charge inside the closed surface

b) the charge residing on insulators inside the closed surface

c) all the charge in the physical system

d) any charge inside the closed surface that is arranged symmetrically

The correct answer is option A. The Guass's law states that the net electric flux through any closed surface is equal to the net charge enclosed by the surface divided by the electric permitivity.