Conjugation between unshared electron pair on oxygen and aromatic ring in phenoxide ion results in:

Explanation

In phenoxide ion, the unshared electron pair on the oxygen atom participates in resonance with the aromatic ring, creating a conjugated system. This resonance imparts partial double bond character to the C-O bond, shortening its bond length. The delocalization of charge across the ion stabilizes the phenoxide ion, making it a more stable base compared to other alkoxide ions. This increased stability of the conjugate base (phenoxide ion) enhances the acidic strength of phenol. Therefore, all the given statements (shorter C-O bond distance, stable base, stronger acidic character) are correct, making 'All of these' the right choice.