Phenols are converted into their salts by aqueous `NaOH` but not by aqueous bicarbonates. The salts are converted into the free phenols by aqueous mineral acids, carboxylic acid or carbonic acids. Most phenols have `K_(a)` value of about `10^(-10)`, and are tremondously more acidic than alcohols. The difference in acidity are due to difference in stablities of reactants and products. Phenol and phenoxide ions contain benzene ring and therefore must be hybrid of Kekuley structures

Being basic, oxygen can share more than a pair of electron with the ring.

Since energy must be supplied to separate opposite charge, the structure of phenols should contain more energy. The net effect of reasonance is therefore to stablise the phenoxide ion to a greater extent than the phenol and thus to shift the equilibrium towards ionization and make `K_(a)` larger than for an alcohol.
Correct order of acidity is

Options

A.
B.
C.
D. Both B and C

Answer

D