Which one of the following compounds is non-aromatic?

Step-by-step solution

For the following ion/compounds The main difference between aromatic antiaromatic and nonaromatic is that aromatic means having a delocalized pi electron system with (4n +2) electrons and antiaromatic means having a delocalized pi electron system with 4 electrons whereas nonaromatic means there is no delocalized electron system in that molecule.