The place of blood formation in human body is :

Options

A. Bone Marrow
B. Spleen
C. Heart
D. Liver

Explanation

**Step-by-Step Solution:**

1. **Understanding Blood Formation**: Blood is composed of red blood cells (RBCs), white blood cells (WBCs), and platelets. These components are crucial for various functions in the body, including oxygen transport, immune response, and blood clotting.

2. **Identifying the Site of Blood Formation**: The primary site for the formation of blood cells in the human body is known as bone marrow.

3. **Location of Bone Marrow**: Bone marrow is found within the cavities of bones. It is especially abundant in major bones such as the femur, pelvis, and sternum.

4. **Characteristics of Bone Marrow**: Bone marrow is a soft and spongy tissue located in the center of bones. This structure is essential for its function in producing blood cells.

5. **Percentage of Blood Cells Produced**: Approximately 95% of the blood cells in the human body are produced in the bone marrow, which emphasizes its importance in hematopoiesis (the formation of blood cells).

6. **Conclusion**: Therefore, the correct answer to the question regarding the place of blood formation in the human body is bone marrow.

**Final Answer**: The place of blood formation in the human body is the **bone marrow**.

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