Explanation:Nitro Group : The nitro group is generally resistant to reduction by diborane under typical reaction conditions. Diborane is not a strong enough reducing agent to convert the nitro group to an amine . Therefore, the nitro group will remain unchanged in this reaction.Carboxylic Acid Group ( COOH ): Diborane is highly effective at reducing carboxylic acids to primary alcohols. The carboxylic acid group COOH on the benzene ring will be reduced to a hydroxymethyl group . This occurs because the carboxylic acid has a free hydroxyl group that can coordinate with diborane, making it highly susceptible to reduction.Ester Group : The ester group is less reactive toward diborane compared to the carboxylic acid. This lower reactivity is due to the resonance stabilization of the ester, which makes the carbonyl carbon less electrophilic and less prone to nucleophilic attack by diborane. Moreover, the ester lacks a free hydroxyl group, which further limits its interaction with diborane. As a result, the ester group is likely to remain intact during the reaction.