This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General obstetrics, Subject name: Gynaecology & Obstetrics
[{'content': 'Uterine contractions are clinically palpable when their intensity is more than : \nSelect and explain. \nA. 10 mm of Hg, B. 15 mm of Hg, C. 20 mm of Hg, D. 40 mm of Hg', 'role': 'user'}, {'content': "Answer: A \nExplanation: The intensity of uterine contractions describes the degree of uterine systole. During pregnancy uterus is quiescent, the tone is 2-3mmHg. During the first stage of labor it varies from 8-10 mmHg, it is inversely propoional to relaxation. D.C.DUTTA'S TEXTBOOK OF OBSTETRICS,pg no:117,7th edition", 'role': 'assistant'}]