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 foetal blood is separated from syncytiotrophoblast with all except: 
Select and explain. 
A. Fetal blood capillary membrane, B. Mesenchyme of intervillous blood space, C. Cytotrophoblast, D. Decidua parietalis
D: Decidua parietalis
Answer: D: Decidua parietalis 
Explanation: The maternal blood in the lacuna is never in direct contact with fetal blood. They are separated by:

Syncytiotrophoblast
Cytotrophoblast
Basement membrane
Mesoderm
Endothelium of fetal capillaries

Together called as placental barrier or membrane (0.025 mm)