(A) The acidity of a compound depends on the stability of its conjugate base.
$1$. Carboxylic acids $(R-COOH)$ lose a proton to form a carboxylate ion $(R-COO^-)$. This ion is stabilized by two equivalent resonance structures where the negative charge is delocalized over two highly electronegative oxygen atoms.
$2$. Phenols $(C_6H_5OH)$ lose a proton to form a phenoxide ion $(C_6H_5O^-)$. Although the phenoxide ion is stabilized by resonance,the negative charge is delocalized onto the less electronegative carbon atoms of the benzene ring,making it less stable than the carboxylate ion.
$3$. Alcohols $(R-OH)$ form alkoxide ions $(R-O^-)$ upon losing a proton. These ions have no resonance stabilization,making them the least stable and thus the least acidic.
Therefore,due to the greater stability of the carboxylate ion compared to the phenoxide and alkoxide ions,carboxylic acids are more acidic.