**Core Concept**
The period of embryogenesis, also known as embryonic development, is a critical phase in the development of a multicellular organism from a fertilized egg. This period is characterized by rapid cell division, differentiation, and growth, laying the foundation for the formation of various tissues and organs.

**Why the Correct Answer is Right**
The correct answer is **B. 8 weeks**. This is because the period of embryogenesis in humans extends from fertilization to approximately 8 weeks of gestation. During this period, the embryo undergoes significant morphological changes, including gastrulation, neurulation, and the formation of major organs. The 8-week mark is a crucial milestone, as it marks the end of embryogenesis and the beginning of fetal development.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because the period of embryogenesis does not extend beyond 8 weeks. While fetal development continues beyond this point, the embryonic period itself is limited to 8 weeks.

**Option C:** This option is incorrect because the period of embryogenesis is not the same as the period of fetal development. While these two periods overlap, they are distinct and have different characteristics.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that the embryonic period is a critical window for teratogenic insult, and exposure to teratogens during this period can lead to significant developmental abnormalities.

**Correct Answer:** B. 8 weeks