Aromatic compounds are chemical compounds that consist of conjugated planar ring systems accompanied by delocalized pi-electron clouds in place of individual alternating double and single bonds. In a simpler term, aromatic compounds are compounds of Benzene and its derivatives.e.g Benzene, Phenol, Toluene, xylene, anthracene, Naphthalene etc all cyclically conjugated.

The compound in option A is called phenol - a benzene ring with an hydroxyl group (OH) attached to C-1.