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
In the early pregnancy, the doubling time of HCG concentrations in plasma is : 
Select and explain. 
A. 12 hours, B. 48 hours, C. 72 hours, D. 96 hours
B: 48 hours
Answer: B: 48 hours 
Explanation: 48 hours