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
NOT a definitive sign of pregnancy: 
Select and explain. 
A. Fetal skeleton on X-ray, B. Fetal hea sounds, C. Ultrasound examination, D. Amenorrhea
D: Amenorrhea
Answer: D: Amenorrhea 
Explanation: 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