**Core Concept**
The normal turnover rate of the epidermis refers to the time it takes for the outermost layer of the skin, the stratum corneum, to be replaced entirely. This process is crucial for maintaining the integrity and health of the skin.

**Why the Correct Answer is Right**
The correct answer is D. 8 weeks. This is because the epidermis is a dynamic tissue that undergoes continuous renewal through a process called cell turnover. The rate of cell turnover is influenced by various factors, including hormonal changes, age, and environmental factors. The stratum corneum, the outermost layer of the epidermis, is made up of dead skin cells that are constantly being shed and replaced by new cells from the underlying layers. The average lifespan of a skin cell in the stratum corneum is approximately 28 days, which corresponds to a turnover rate of around 8 weeks.

**Why Each Wrong Option is Incorrect**
**Option A:** 2 weeks is too short, as it would imply an extremely rapid turnover rate that is not biologically plausible.
**Option B:** 4 weeks is still too short, as it would not allow sufficient time for the complete replacement of the stratum corneum.

**Clinical Pearl / High-Yield Fact**
It's worth noting that the rate of skin cell turnover can be influenced by various factors, including hormonal changes, age, and environmental factors. For example, the rate of skin cell turnover is slower in older individuals and in areas of the skin that are exposed to the sun.

**Correct Answer:**
✓ Correct Answer: D. 8 weeks