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: Gynaecology & Obstetrics
[{'content': 'Decidual casts bleeding per vaginum suggestive of : \nSelect and explain. \nA. Inevitable aboion, B. Threatened aboion, C. Tubal aboion, D. None', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Tubal aboion', 'role': 'assistant'}]