Which of the following compounds is not aromatic?

Aromaticity of a compound can be decided by Huckel's rule. In cyclopentadienyl cation (b), resonance takes place as follows:Hence, is anti-aromatic does not follow Huckel's rule as it has conjugated 4π-electron (4nπ, n = 1) system. Rest of the species are aromatic as each of them belongs to 6rt-electron [(4m + 2) π, n = 1] system.