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': "Osiander's sign is positive in? \nSelect and explain. \nA. First trimester of pregnancy, B. Fibroid, C. Hydatidiform mole, D. Abdominal pregnancy", 'role': 'user'}, {'content': "Answer: A \nExplanation: The pelvic changes are diverse and appear at different periods during pregnancy. There is increased pulsation, felt through the lateral fornices at 8th week called Osiander's sign. Similar pulsation is also felt in acute pelvic inflammatory disease. Ref: Textbook of Obstetrics D.C.Dutta 6th Ed Page 65.", 'role': 'assistant'}]