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
The fetal blood is separated from maternal blood with all except : 
Select and explain. 
A. Extra embryonic mesoderm, B. Syncytio trophoblast, C. Cyto trophoblast, D. Decidua parietalis
D: Decidua parietalis
Answer: D: Decidua parietalis 
Explanation: Decidua parietalis