a
The increasing order of the acidity of the carboxylic acids is \(III < II< IV< I\) . In aromatic acids, electron withdrawing groups like \(-Cl,\, -CN,\, -NO_2\) increases the acidity, whereas electron releasing groups like \(- CH_3,\, -OH,\, -OCH_3,\, -NH_2\) decreases the acidity.