The prenatal period begins with which of the following events?

• A. Fertilization
• B. Gastrulation
• C. Birth
• D. Implantation

Answer: (A)

Verified step by step guidance

1. Understand the prenatal period: The prenatal period refers to the time of development that occurs before birth, starting from the formation of a zygote and continuing through embryonic and fetal development.
2. Define fertilization: Fertilization is the process where a sperm cell and an egg cell combine to form a zygote, marking the beginning of the prenatal period. This is the first step in human development.
3. Clarify the role of gastrulation: Gastrulation is a later developmental event during the embryonic stage, where the three germ layers (ectoderm, mesoderm, and endoderm) are formed. It does not mark the beginning of the prenatal period.
4. Explain implantation: Implantation occurs when the zygote (now a blastocyst) attaches to the uterine wall, allowing for further development. While important, it happens after fertilization and does not initiate the prenatal period.
5. Discuss birth: Birth is the end of the prenatal period, marking the transition to the postnatal period. It is not the event that begins the prenatal period.