Which of the following aqueous solutions dissolves phenol by forming a salt?

Phenol ($\mathrm{p}{K}_a$ 10.0) is a weak acid. It reacts with a base whose conjugate acid is weaker than phenol. $\mathrm{OH}{}^{-}$ (conjugate acid water, 15.7) qualifies, giving sodium phenoxide. $\mathrm{HCO}{}_3{}^{-}$ (conjugate acid $\mathrm{H}{}_2\mathrm{CO}{}_3$, 6.4) does not, and $\mathrm{NaCl}$ and $\mathrm{HCl}$ are not bases.