The Correct is C₆H₅O⁻ : It is the most commonly bonded to the acidic hydrogen , and O2 is the most element bonded to the acidic hydrogen.
The explanation:
According to the table below we can see that the Ka ( the acid dissociation constant) for the Phenol is the smallest one.
when the Ka expression for this chemical reaction:
C₆H₅OH(aq) ⇄ C₆H₅O⁻(aq) + H⁺(aq)
is
Ka = [C₆H₅O⁻] · [H⁺] / [C₆H₅OH]
So, the water solution of the phenol has a very low equilibrium concentration of H ions [H+] , So C₆H₅O⁻ is the element which most commonly bonded to the acidic hydrogen.