What happens during implantation?

1. Sperm are deposited into the vagina.

2. The embryo is surrounded by the amniotic sac.

3. Sperm fertilize an egg.

4. The blastocyst attaches to the wall of the uterus.

Which action occurs in the third stage of cell division a. the nuclear material of a cell is copied exactly b. the nuclear membrane disappears c. the cell forms two nuclei or d. the nuclear material separates, with half moving to wither side of the cell