Why is benzene nonpolar?

Benzene is nonpolar because it is a symmetrical molecule in which all the bond cancel.
The structure of benzene is
It is a flat molecule with the shape of a regular hexagon.
We could say that benzene is nonpolar because it is a hydrocarbon that contains only ##”C-C”## and ##”C-H”## bonds, and hydrocarbons are nonpolar.
But ##”C”## is slightly more electronegative than ##”H”## (by 0.35 units), so a ##”C-H”## bond is very slightly polar and has a small dipole moment.
However, each ##”C-H”## bond has a partner that points in exactly the opposite direction.
The bond dipoles cancel exactly, so benzene has a zero dipole moment.
This makes benzene a nonpolar molecule.