Final answer:
Option C, zygote forms, blastocyst implants in the uterus, heart begins beating, sex organs become visible, and lungs can breathe air, describes the correct sequence of prenatal development.
Step-by-step explanation:
The correct sequence describing prenatal development is option C: zygote forms, blastocyst implants in the uterus, heart begins beating, sex organs become visible, and lungs can breathe air.
In the embryonic stage, the zygote forms and becomes a blastocyst, which then implants in the uterus. The heart starts beating, followed by the development of sex organs and the ability to breathe air.