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': 'Regarding braxton Hicks contractions, all are wrong except \nSelect and explain. \nA. Intensity varies between 20 and 40 mmHg., B. Occur in early pregnancy and may be palpated in second trimester., C. These contractions become more regular later in pregnancy., D. Both 2 and 3.', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Braxton Hick contractions are usually non-rhythmic, their intensity varies between 5 and 25 mmHg.\nTheir number increases during last week, but are not regular.', 'role': 'assistant'}]