For a specie to be a strong base, the corresponding conjugate acid should be weak.
$\mathit{O}\mathit{H}-+\mathit{H}+\to \underset{\mathit{w}\mathit{a}\mathit{t}\mathit{e}\mathit{r}}{{\mathit{H}}_2\mathit{O}}$
$\mathit{O}\mathit{R}-+\mathit{H}+\to \underset{\mathit{a}\mathit{l}\mathit{c}\mathit{o}\mathit{h}\mathit{o}\mathit{l}}{\mathit{R}\mathit{O}\mathit{H}}$
${\mathit{C}}_6{\mathit{H}}_5\mathit{O}-+\mathit{H}+\to \underset{\mathit{p}\mathit{h}\mathit{e}\mathit{n}\mathit{o}\mathit{l}}{{\mathit{C}}_6{\mathit{H}}_5\mathit{O}\mathit{H}}$
${\mathit{C}}_6{\mathit{H}}_5\mathit{O}-\left(\mathit{m}-\mathit{N}{\mathit{O}}_2\right)+\mathit{H}+\to \underset{\mathit{m}-\mathit{n}\mathit{i}\mathit{t}\mathit{r}\mathit{o}\mathit{p}\mathit{h}\mathit{e}\mathit{n}\mathit{o}\mathit{l}}{\mathit{H}\mathit{O}{\mathit{C}}_6{\mathit{H}}_5\left(\mathit{m}-\mathit{N}{\mathit{O}}_2\right)}$
Since the acidity of phenol is higher than aliphatic alcohol. Also, the acidity of water is higher than alcohol. Thus least acidic product is ROH.
As weaker acid has a strong conjugate base or vice-versa, $\mathit{R}\mathit{O}-$ will be the strongest base among all.