Erythropoiesis starts in

Options

A. liver
B. spleen
C. red bone marrow
D. kidney

Answer

**Step-by-Step Solution:**

1. **Understanding Erythropoiesis**: Erythropoiesis is the process of producing red blood cells (RBCs). The term comes from the Greek words "erythro," meaning red, and "poiesis," meaning to make or produce.

2. **Identifying the Stimulus**: This process is stimulated by a decrease in oxygen levels in the blood. When oxygen levels drop, it triggers a response in the body.

3. **Role of the Kidney**: The kidneys detect the low oxygen levels and respond by producing a hormone called erythropoietin (EPO). This hormone is crucial for the stimulation of red blood cell production.

4. **Action of Erythropoietin**: Erythropoietin acts on precursor cells in the bone marrow, which are responsible for the production of red blood cells.

5. **Location of Erythropoiesis**: The actual production of red blood cells occurs in the hemopoietic tissues, specifically in the red bone marrow.

6. **Conclusion**: Based on the information gathered, erythropoiesis starts in the red bone marrow.

**Final Answer**: Erythropoiesis starts in **C. Red Bone Marrow**.

---