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': 'NOT a definitive sign of pregnancy: \nSelect and explain. \nA. Fetal skeleton on X-ray, B. Fetal hea sounds, C. Ultrasound examination, D. Amenorrhea', 'role': 'user'}, {'content': "Answer: D \nExplanation: Amenorrhea can be due to many reasons including pregnancy but also PCOS, Tuberculosis, Hypothalamic causes like Kallman's & Sheehan's syndrome , Pseudocyesis etc Remaining 3 are the definite signs of Pregnancy", 'role': 'assistant'}]