Final answer:
The heating of phenyl-methyl ether with HI produces phenol and methyl iodide, with phenol being the correct answer to the student's query.
Step-by-step explanation:
The heating of phenyl-methyl ether with HI primarily results in the cleavage of the ether, leading to the formation of phenol and methyl iodide. In this reaction, the iodide replaces the methoxy group (CH3O-) attached to the benzene ring. Since phenol has an -OH group attached to an sp²-hybridized carbon of a benzene ring and is a key product in this reaction, the correct answer is (d) phenol.