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
All are true regarding fetal skeletal mineralization except 
Select and explain. 
A. 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.
B: Calcium required by fetus is only 10 % of maternal, skeletal calcium.
Answer: B: Calcium required by fetus is only 10 % of maternal, skeletal calcium. 
Explanation: Fetal calcium requirement is only 3 % of total calcium held within maternal skeleton.