Answer:
Aromatization leads to evolution of carbon dioxide
Explanation:
In p-hydroxybenzoic acid, -OH and -COOH groups remain in para position.
The directing effect of -OH and -COOH group act synergistically to react with three equivalent of bromine.
In para position of -OH group, -COOH remains attached along with a Br atom in a same carbon atom. During aromatization of benzene group, this -COOH group decomposes to give carbon dioxide.
Reaction scheme has been shown below.
