Phenol and benzyl alcohol are two different chemical compounds that have distinct chemical structures and properties. Let's analyze the given options one by one to understand why the correct answer is option 'D' (None of these).

a) Functional Isomers:
Functional isomers are compounds that have the same molecular formula but differ in the functional group present. In the case of phenol and benzyl alcohol, both compounds have the same functional group, which is an -OH group (hydroxyl group). Therefore, they cannot be considered functional isomers.

b) Homologous:
Homologous compounds are a series of organic compounds that have the same functional group and a similar chemical structure. They differ from each other by a common structural unit, such as a -CH2 group. Phenol and benzyl alcohol do not belong to the same homologous series as they have different structures and functional groups.

c) Position Isomers:
Position isomers are compounds that have the same molecular formula and functional group but differ in the position of the functional group in the molecule. For example, in the case of butanol and isobutanol, both compounds have the same molecular formula C4H10O and the same functional group -OH, but the position of the -OH group is different in each compound. However, in the case of phenol and benzyl alcohol, the functional group -OH is attached to different parts of the molecule. In phenol, the -OH group is directly attached to the benzene ring, whereas in benzyl alcohol, the -OH group is attached to a methyl (-CH3) group attached to the benzene ring. Hence, they cannot be considered position isomers.

Therefore, the correct answer is option 'D' (None of these) as neither functional isomers, homologous compounds, nor position isomers accurately describe the relationship between phenol and benzyl alcohol.