Which gland is active in young children and then reduces in size but functions in the maturation of T-cells ?

Explanation

**Step-by-Step Solution:**

1. **Identify the Gland:** The question asks for a gland that is active in young children and is involved in the maturation of T-cells.

2. **Understanding T-cells:** T-cells, or T-lymphocytes, are a type of white blood cell that plays a crucial role in the immune response. They are essential for the adaptive immune system.

3. **Locate the Gland:** The gland responsible for the maturation of T-cells is known as the thymus gland.

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