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': 'All are true regarding fetal skeletal mineralization except \nSelect and explain. \nA. Approximately 30g of calcium is needed especially during 3rd trimester., B. Calcium required by fetus is only 10 % of maternal, skeletal calcium., C. Amount of calcium absorbed increases to 400mg / day in the third trimester., D. PTH plasma concentration is decreased in first trimester, but increases progressively later.', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Fetal calcium requirement is only 3 % of total calcium held within maternal skeleton.', 'role': 'assistant'}]