This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Dermatitis, Subject name: Dental
[{'content': "Casal's paint necklace is caused by \nSelect and explain. \nA. Pellagra, B. SLE, C. Lichen planus, D. Pernicious anemia", 'role': 'user'}, {'content': "Answer: A \nExplanation: Pellagra is characterised by deficiency of tryptophan, leading to photosensitivity on exposure to uv light three D'sof pellagra diarrhoea dermatitis dementia some impoant cutaneous features gauntlet of pellagra-sun burn over Dorsum of hands castles necklace- dermatitis over neck extending to anterior chest. cheliosis scarlet glossitis and stomatitis Ref Harrison20th edition pg 1345", 'role': 'assistant'}]