Implantation Which of the following sequences correctly describes prenatal development? A. blastocyst implants in uterus, zygote forms, heart begins beating, lungs can breathe air, sex organs become visible B. blastocyst implants in the uterus, zygote forms, heart begins beating, sex organs become visible, lungs can breathe air C. zygote forms, blastocyst implants in the uterus, heart begins beating, sex organs become visible, lungs can breathe air D. zygote forms, blastocyst implants in the uterus, sex organs become visible, heart begins beating, lungs can breathe air 3. Which of the following correrti​