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': "Obsolete method for testing tubal patency is : \nSelect and explain. \nA. Hystero salpingogram, B. Chromo salpingogram, C. Rubin's test, D. None of the above", 'role': 'user'}, {'content': "Answer: C \nExplanation: Rubin's test", 'role': 'assistant'}]