Fetus is a transplant of foreign tissue in the mother. However transplant (fetus) is tolerated and not rejected by mother, because of the following except one:- a) placental trophoblast expresses HLA-G genes- b) Antibodies against fetal protein do not develop- c) Placental trophoblast expresses class I and II genes- d) Fas ligand on placeenta bonds T cells causes them to undergo apoptosis