**Core Concept**
The embryonic period, also known as organogenesis, is a critical phase in human development where the major organs and body structures begin to form. This period is characterized by rapid cell division, differentiation, and morphogenesis, laying the foundation for the development of a complex organism.

**Why the Correct Answer is Right**
The embryonic period spans from the third week of gestation to the end of the eighth week. During this time, the embryoblast differentiates into three primary germ layers: ectoderm, mesoderm, and endoderm. These layers give rise to all tissues and organs in the body, including the nervous system, cardiovascular system, and digestive system. The precise timing and coordination of cellular differentiation and morphogenesis are crucial for the proper development of these organs.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not specify the correct timeframe for the embryonic period.
**Option B:** This option is incorrect because it does not accurately represent the duration of the embryonic period.
**Option C:** This option is incorrect because it suggests a timeframe that is too short for the embryonic period.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that the embryonic period is a critical window for organogenesis, and any disruptions or abnormalities during this time can lead to congenital anomalies or developmental disorders.

**Correct Answer:** C. 8 weeks.