Benzene is best described by:

Benzene's true bonding is a **resonance hybrid** of two equivalent Kekulé structures (the alternation of double bonds drawn either way). All six C-C bond lengths are equal (about $1.39$ Å, intermediate between a typical C-C single bond at $1.54$ Å and C=C double bond at $1.34$ Å). The modern picture: six sp²-hybridised carbons form a planar hexagonal ring; each contributes one unhybridised $p$ orbital perpendicular to the ring. These overlap sideways to form a delocalised $\pi$ system (a doughnut of electron density above and below the ring). Kekulé's original alternating-single-double picture (option A) underestimates the symmetry: the molecule has 6-fold rotational symmetry, which only the resonance/delocalised picture captures.