Anaemia is caused by the deficiency of

Options

A. oxygen
B. enzymes
C. vit E
D. iron

Answer

### Step-by-Step Solution:

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

2. **Identifying the Causes**: The question asks about the deficiency that causes anemia. Common causes include deficiencies in iron, vitamin B12, folate, and other nutrients. However, in this context, we will focus on iron.

3. **Role of Iron in Hemoglobin**: Hemoglobin is the protein in red blood cells responsible for transporting oxygen. It contains a heme group, which includes iron as a central component. Iron binds to oxygen, allowing it to be transported throughout the body.

4. **Consequences of Iron Deficiency**: When there is insufficient iron in the body, the production of hemoglobin is impaired. This results in fewer healthy red blood cells being produced, leading to anemia.

5. **Conclusion**: Therefore, the deficiency that primarily causes anemia is iron deficiency.

### Final Answer:
Anemia is caused by the deficiency of **iron**.

---