It is semi permeable allowing certain adams to cross through and to their cells.
Because of the fact that female mammals have chromosomes from both parents (from the father and from the mother) and all cells have the same inactivated X chromosome female mammals are considered to be mosaic <span>of the maternal and paternal cells.</span>
I personally think that it's D. If this is right you're welcome. If it's wrong feel free to delete this answer :p