Anemia is caused due to the deficiency of

Options

A. Folic acid
B. Vitamin `B_12`
C. Hemoglobin
D. All of these

Answer

### Step-by-Step Solution:

1. **Understanding Anemia**: Anemia is a condition characterized by a deficiency in the number or quality of red blood cells (RBCs) in the body. This leads to a reduced capacity of the blood to carry oxygen to tissues.

2. **Identifying the Components of Blood**: Blood is a connective tissue composed of two main parts: plasma (the liquid component) and formed elements (blood corpuscles). The formed elements include red blood cells (RBCs), white blood cells (WBCs), and platelets.

3. **Role of Hemoglobin**: Hemoglobin is an iron-containing protein found in RBCs that is essential for transporting oxygen. A deficiency in hemoglobin directly leads to anemia, as it reduces the blood's oxygen-carrying capacity.

4. **Nutritional Deficiencies Leading to Anemia**:
- **Folic Acid (Vitamin B9)**: A deficiency in folic acid can lead to megaloblastic anemia, where the RBCs are larger than normal and not fully developed.
- **Vitamin B12 (Cobalamin)**: This vitamin is crucial for the maturation of RBCs. A deficiency can also lead to anemia due to improper RBC formation.

5. **Conclusion**: Given the options:
- Hemoglobin deficiency leads to anemia.
- Folic acid deficiency can cause megaloblastic anemia.
- Vitamin B12 deficiency can lead to anemia due to impaired RBC maturation.

Therefore, anemia can be caused by deficiencies in hemoglobin, folic acid, and vitamin B12.

6. **Final Answer**: The correct answer to the question "Anemia is caused due to the deficiency of" is **option 4: all of these**.

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