This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Radiology
[{'content': 'T sign is seen in \nSelect and explain. \nA. Genito urinary TB, B. PCOD, C. Spina bifida, D. Membrane in twin pregnancy', 'role': 'user'}, {'content': 'Answer: D \nExplanation: T sign - membrane in a monochoronic twin pregnancy.', 'role': 'assistant'}]