This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Fetus Placenta & Fetal Membrane, Subject name: Gynaecology & Obstetrics
What is the pH of amniotic fluid? 
Select and explain. 
A. 6.5-7, B. 7.1-7.3, C. 7.4-7.8, D. 7.8-8.1
B: 7.1-7.3
Answer: B: 7.1-7.3 
Explanation: Ans. B. 7.1-7.3Properties of amniotic fluid:a. pH:7.1-7.3b. Specific gravity: 1.010c. Osmolarity: 250mOsmol/l--a sign of fetal maturity.