This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Psoriasis, Subject name: Skin
[{'content': 'Oil drop sign of nail is seen in? \nSelect and explain. \nA. Lichen planus, B. Dermatophytes, C. Lupus vulgaris, D. Psoriasis', 'role': 'user'}, {'content': "Answer: D \nExplanation: Ans. (d) PsoriasisRef: Lippincott's Primary Care Dermatology p 47, Bar an and Dawber's Disease of the Nails ad their Management by Robert Baran, David A. R. de Berker, Mark Holzberg, Luc Thomas ch-6", 'role': 'assistant'}]