Benzene was once drawn with alternating single and double bonds. Which of the statements below about its structure and aromaticity are correct?

• Statement I: Benzene is a planar molecule in which every carbon atom is sp² hybridised.
• Statement II: Cyclooctatetraene is aromatic because it is cyclic and fully conjugated.
• Statement III: All six carbon–carbon bonds in benzene have the same length, 139 pm.
• Statement IV: Benzene readily undergoes addition reactions in preference to substitution.