Which of the following alcohols are more acidic than ethanol in aqueous solution?

A -I substituent stabilises the alkoxide ion, so $\mathrm{CF}{}_3\mathrm{CH}{}_2\mathrm{OH}$, $\mathrm{ClCH}{}_2\mathrm{CH}{}_2\mathrm{OH}$ and $\mathrm{Cl}{}_3\mathrm{CCH}{}_2\mathrm{OH}$ are more acidic than ethanol. The three methyl groups of tert-butyl alcohol are +I and also hinder solvation of the alkoxide, so it is less acidic.