This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Diagnosis of Pregnancy, Subject name: Gynaecology & Obstetrics
[{'content': 'Dusky hue of vestibule and ant vaginal wall is \nSelect and explain. \nA. Chadwick sign, B. Osiandersign, C. Goodel sign, D. Hegar sign', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. (a) Chadwick sign', 'role': 'assistant'}]