**Core Concept**
Body iron stores are primarily regulated by the hormone hepcidin, which controls the absorption and mobilization of iron from various sources. This complex system ensures that iron is available for erythropoiesis, while also preventing excessive iron accumulation.

**Why the Correct Answer is Right**
The correct answer choice is related to the iron regulatory protein, ferroportin. Hepcidin binds to ferroportin, causing its internalization and degradation, which in turn reduces iron export from enterocytes and macrophages. This results in decreased iron absorption from the gut and mobilization from storage sites. The correct answer choice reflects this mechanism of action.

**Why Each Wrong Option is Incorrect**
* **Option A:** This choice is incorrect because it does not accurately describe the regulation of body iron stores.
* **Option B:** This option is also incorrect because it does not provide a clear mechanism for regulating body iron stores.
* **Option D:** This choice is incorrect because it does not accurately describe the role of ferroportin in iron regulation.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that hepcidin plays a crucial role in regulating body iron stores, and its dysregulation can lead to disorders such as iron deficiency anemia or hemochromatosis.

**Correct Answer:** C.