Which of the following compounds will provide a tertiary alcohol on reaction with excess of CH$$_3$$MgBr followed by hydrolysis?

The reaction involves the Grignard reagent $$\mathrm{CH_3MgBr}$$, which acts as a strong nucleophile and strong base.

Compound $$\mathrm{A}$$ is an ester, $$\mathrm{Phenyl\ Acetate}$$. Esters react with excess Grignard reagent to form tertiary alcohols.

In the first step, one equivalent of $$\mathrm{CH_3MgBr}$$ attacks the ester carbonyl carbon.

Nucleophilic acyl substitution occurs, expelling the phenoxy group $$\mathrm{(-OC_6H_5)}$$ and forming $$\mathrm{Acetone\ (CH_3COCH_3)}$$.

Since the Grignard reagent is present in excess, a second equivalent attacks the ketone carbonyl carbon.

Acidic hydrolysis protonates the alkoxide intermediate to form $$\mathrm{2\text{-}Methyl\text{-}2\text{-}propanol}$$ with structure $$\mathrm{(CH_3)_3C-OH}$$, which is a tertiary alcohol.

In compound $$\mathrm{B}$$, the terminal alkyne proton is highly acidic.

Hence, $$\mathrm{CH_3MgBr}$$ first undergoes an acid-base reaction, deprotonating the alkyne instead of forming a tertiary alcohol.

Therefore, the correct option is $$\mathrm{A}$$.