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': 'Which among the following is the MOST diagnostic sign of pregnancy? \nSelect and explain. \nA. Amenorrhoea, B. Quickening, C. Foetal hea sounds, D. Distention of abdomen', 'role': 'user'}, {'content': "Answer: C \nExplanation: Presence of fetal hea sounds is an absolute diagnostic sign of pregnancy. Other absolute signs of pregnancy are: Palpation of fetal pas and perception of active fetal movements Ultrasonographic evidence of gestational sac and embryo in early pregnancy and later. Probable signs: Change in size, shape and consistency of uterus Softening of cervix Osiander's sign, Chadwick's sign, Goodell sign Abdominal enlargement Braxton Hicks contraction External and internal ballottement Ref: Essential of Obstetrics By Arulkumaran page 39", 'role': 'assistant'}]