For solvolysis, the solvent has to break the bond between the leaving group and the carbon to which the leaving group is attached. And it is given that the proposed pathway or mechanism is via SN2. In an SN2, hydroxide is a very poor leaving group. In aniline and chlorobenzene, the substituent on the benzene ring are attached to a relatively more electronegative sp2 hybrid carbon. So between 1-phenylethanol and 1- phenylethylchloride, the latter is more suited for an SN2 solvolysis.