This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Skin
[{'content': 'Substance used a bleaching agent in melasma is ? \nSelect and explain. \nA. Hydroquinone, B. Hydroxychloroquin, C. Hydrogen peroxide, D. Benzoyl peroxide', 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans. is'a' i.e., Hydroquinone (Ref : IADVL textbook of dermatology 3'd /e p. 1607) Depigmenting agents (Bleaching agents):Hydroquinone 2-5%Ascorbic acidRetinoidsLiquorice extractAzelaic acid (10-20%)Kozic acid (1-4%)ArbutinNicotinamide", 'role': 'assistant'}]