The question asks:

Which compound, on treatment with HBr, will give a phenol?

However, the actual structures/options A, B, C, and D are missing in the prompt. Since this is an organic chemistry identification question, the answer depends completely on the structures given in the options.

Key concept

Phenol can be obtained when an aryl–alkyl ether is cleaved by HBr/HI.

For example, anisole reacts with HBr as:

This happens because in aryl–alkyl ethers, the bond cleaves at the alkyl–O side, not the aryl–O side. Thus:

• Aryl–alkyl ether $\rightarrow$ gives phenol
• Dialkyl ether $\rightarrow$ gives alcohol + alkyl bromide
• Phenol itself does not get formed unless the substrate contains an aryl–O–alkyl linkage

Therefore

The correct option should be the one that is an aryl–alkyl ether (such as anisole or substituted anisole).

But since the option structures are not visible, I cannot independently verify whether option A is indeed that compound.

Comparison with stored answer

The stored correct answer is A, but due to the missing options, this cannot be fully checked from the provided data.

If option A is an aryl–alkyl ether, then the stored answer is correct.