This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General obstetrics, Subject name: Gynaecology & Obstetrics
[{'content': 'Thickness of placental barrier in early pregnancy \nSelect and explain. \nA. 0.5 mm, B. 0.05 mm, C. 0.025 mm, D. 0.25 mm', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Placental barrier in early pregnancy consists of Synctiotrophoblast Cytotrophoblast Basement membrane Stromal tissue Endothelium of fetal capillary wall It is about 0.025 mm thick Ref: Dutta Obs 9e pg 30.', 'role': 'assistant'}]