The Trophoblast Helps an Early Human Embryo Embed Itself in the Mother's

The trophoblast helps an early human embryo embed itself in the mother's endometrium

A) after the somites have appeared.
B) by secreting enzymes that break down proteins and allow it to enter.
C) using cilia extending from the zona pellucida.
D) by excreting hydrophobic lipids that cause it to drop out of the uterine fluid and press against the uterine wall.
E) None of the above