Both alcohols and phenols contain a hydroxyl group, but phenols are more acidic than alcohols. Whereas the acid strength of aliphatic alcohols mainly depends upon the inductive effects, and acid strength of phenols depends upon a combination of both inductive and resonance effects of the substituent and its position on the benzene ring.

Identify the strongest acid.

o-Methoxyphenol p-Methoxyphenol m-Methoxyphenol Phenol

m-Methoxyphenol

m-Methoxy phenol is the strongest acid.  Methoxy group at meta position exerts an only-I effect. Due to this, it withdraws electrons from all the nuclear position of the benzene ring including the one holding the $O-H$ group consequently, electron density in the $O-H$ bond decreases.  Hence, m-methoxy phenol becomes more acidic than o and p-methoxy phenols.