Ageing starts with disapperance of

Options

A. Spleen
B. Pituitary gland
C. Thymus
D. Parathyroid gland

Answer

### Step-by-Step Solution:

1. **Understanding the Question**: The question asks about what disappears as a person ages, which is linked to the process of aging.

2. **Identifying the Relevant Theory**: The immunological theory of aging is relevant here. This theory suggests that the immune system plays a crucial role in the aging process.

3. **Role of the Thymus Gland**: The thymus gland is identified as a primary lymphoid organ responsible for the maturation of T lymphocytes (T cells), which are essential for the immune response.

4. **Development and Regression of the Thymus**: In children, the thymus gland is fully developed and plays a significant role in the immune system. However, as a person ages, the thymus gland undergoes regression.

5. **Disappearance of the Thymus Gland**: By old age, the thymus gland significantly decreases in size and may almost disappear, leading to a decline in the immune function.

6. **Conclusion**: Therefore, according to the immunological theory of aging, the disappearance of the thymus gland is associated with the aging process.

### Final Answer:
Aging starts with the disappearance of the thymus gland.

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