This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Miscellaneous, Subject name: Social & Preventive Medicine
[{'content': 'Casals Necklace pattern is seen in \nSelect and explain. \nA. Thiamine deficiency, B. Riboflavin deficiency, C. Niacin deficiency, D. All of the above', 'role': 'user'}, {'content': 'Answer: C \nExplanation: (C) Niacin deficiency # Casal collar or Casal Necklace is a clinical sign in which there is an erythematous pigmented skin rash in the distribution of a broad collar (dermatomes C3 and C4). It is seen in patients with pellagra.', 'role': 'assistant'}]