This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Vitamins, Subject name: Social & Preventive Medicine
[{'content': 'Pellagra is caused by deficiency of: \nSelect and explain. \nA. Thiamine, B. Niacin, C. Biotin, D. Ascorbic acid', 'role': 'user'}, {'content': "Answer: B \nExplanation: Ans. (b) NiacinRef: K. Park 23rd ed. / 619* Pellagra is caused by deficiency of Vitamin B3 (Niacin).* It is seen commonly in maize eating populations because maize is deficient in tryptophan which is usually converted to niacin.* Therefore maize eaters develop deficiency of Niacin which ultimately leads to pellagra.* 4 D's associated to Pellagra:# Diarrhea# Dermatitis# Dememntia# Death* In severe cases of pellagra Casals Necklace is seen which is a scaly pigmented rash around neck, seems like necklace.", 'role': 'assistant'}]