Key reaction to use

Grignard reagent $CH_3MgBr$ adds a methyl group to carbonyl compounds, and after hydrolysis gives alcohols.

The type of alcohol formed depends on the starting compound:

• From formaldehyde $\rightarrow$ primary alcohol
• From aldehyde (except formaldehyde) $\rightarrow$ secondary alcohol
• From ketone $\rightarrow$ tertiary alcohol
• From esters / acid chlorides with excess Grignard reagent $\rightarrow$ tertiary alcohol (because two alkyl groups from Grignard can ultimately be introduced)

Condition for getting a tertiary alcohol with excess $CH_3MgBr$

Therefore, the compound must effectively behave like:

• a ketone, or
• an ester / acid derivative that on excess Grignard addition gives a tertiary alcohol.

Issue with the given question

The options labeled A, B, C, D are not visible in the prompt; they are blank. So the exact structures cannot be independently evaluated.

Comparison with stored answer

Since the actual options are missing, I cannot derive from the structures which one is correct by direct analysis. However, the stored correct answer is A.

In the absence of visible options, I cannot rigorously verify it from the data provided. But if option A is the ketone/ester/acid derivative among the choices, then it would indeed give a tertiary alcohol with excess $CH_3MgBr$ followed by hydrolysis.