This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Miscellaneous (Gynae), Subject name: Gynaecology & Obstetrics
The foetal blood is separated from the syncytiotrophoblast with all EXCEPT: 
Select and explain. 
A. Foetal blood capillary membrane, B. Mesenchyme inter villous blood space, C. Cytotrophoblast, D. Decidua - parietalis
D: Decidua - parietalis
Answer: D: Decidua - parietalis 
Explanation: (Decidua-parietalis) (25, 36-Duta 6th)Decidua-vera or parietalis - the rest of the deciduas lining the uterine cavity outside the site of implantation.* Foetal blood now circulate through the villi, while maternal blood circulate through intervillous space (69-IBS- Embryology 7th)* Synocytiotrophoblast grows into the endometrium. As endometrium is eroded, some of its blood vessels are opened up, and blood from them fills the lacunar spaces {intervillous space)* Each trabeculus is initially made up entirely by syncytiotrophoblast. Now the cells of the cytotrophoblast begin to multiply and grow into each trabeculus. The trabeculus thus comes to have a central core of cytotrophoblast covered by an outer layer of syncytium. It is surrounded by maternal blood filling the lacunar space. The trabeculus is now called is primary villous.