The correct option is B $$III < II < I < IV$$
Alcohols are more acidic than terminal alkynes. It is evident that the weakest acid of the lot is $$IV$$. Phenols are more acidic than alcohols due to resonance stabilisation of its conjugate base. But Phenols are less acidic than any carboxylic acid.
Hence the correct order of increasing acidity is
Therefore, Option B is correct.