This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: S.T.D., Subject name: Skin
[{'content': 'Groove sign is seen in? \nSelect and explain. \nA. Chancroid, B. Syphilis, C. LGV, D. Psoriasis', 'role': 'user'}, {'content': "Answer: C \nExplanation: Ans. (c) LGVRef: Rook's 8/e, p 34.33, Greenberg's Text-Atlas of emergency medicine by Michael I. Greenberg p. 367, Nord guide to rare diseases, p 8", 'role': 'assistant'}]