Which one of the following compounds has the most acidic nature?

Step-by-step solution

Key Idea Presence of electron withdrawing substituent increases the acidity while electron releasing substituent, when present, decreases the acidity. Phenyl is an electron withdrawing substituent while - CH ₃ is an electron releasing substituent. Moreover, phenoxide ion is more resonance stabilised as compared to benzyloxide ion, thus releases proton more easily. That's why is a strong acid among the given.