Each of the following is treated with excess $\mathrm{CH}{}_3\mathrm{MgBr}$ in dry ether followed by $\mathrm{H}{}_3\mathrm{O}{}^{+}$. Which give a tertiary alcohol?

Ethyl acetate and acetyl chloride add two $\mathrm{CH}{}_3{}^{-}$ groups to give $(\mathrm{CH}{}_3){}_3\mathrm{C}-\mathrm{OH}$. Acetone adds one to give the same tertiary alcohol. Acetaldehyde adds one and gives only the secondary alcohol propan-2-ol.