The correct acidity order of the following is:

Decreasing order of acidic strength is III>IV>II>I
Carboxylic acid is more acidic than phenol. When an electron releasing group is present in the para position to -COOH group in aromatic carboxylic acid, the acidity is reduced. When Cl atom is present in the para position to -OH group in phenol, it increases its acidity. Here Cl atom withdraws electron density from the ring and stabilizes the phenoxide ion. Option A is correct.