The foetal blood is separated from syncytiotrophoblast with all except:: (A) Fetal blood capillary membrane, (B) Mesenchyme of intervillous blood space, (C) Cytotrophoblast, (D) Decidua parietalis
Answer is D. 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)