In old age, immune system becomes weak due to gradually degeneration of :

Options

A. Pineal gland
B. Parathyroid gland
C. Thymus gland
D. Adrenal gland

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks about the degeneration of which gland leads to a weakened immune system in old age.

2. **Identifying the Glands**: The options provided are the pineal gland, parathyroid gland, thymus gland, and adrenal gland. We need to analyze the role of each gland in relation to the immune system.

3. **Role of the Thymus Gland**: The thymus gland is crucial for the immune system. It is responsible for the maturation of T lymphocytes (T cells), which are vital for cell-mediated immunity. The thymus gland secretes thymosins, which are peptide hormones that promote the development and differentiation of T cells.

4. **Impact of Thymus Degeneration**: As individuals age, the thymus gland undergoes degeneration. This leads to a decrease in the production of thymosins, resulting in a reduced number of T cells. Consequently, the immune response weakens, making older adults more susceptible to infections and diseases.

5. **Conclusion**: Based on the information gathered, the correct answer to the question is that the immune system becomes weak due to the gradual degeneration of the **thymus gland**.

**Final Answer**: The immune system becomes weak due to the gradual degeneration of the **thymus gland**.

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