Root hairs are thin-walled slender extensions of root epidermal cells that are present in millions of number at the root.

Answer

**Step-by-Step Solution:**

1. **Understanding Root Hairs:**
- Root hairs are specialized structures found on the roots of plants. They are extensions of the root epidermal cells.

2. **Characteristics of Root Hairs:**
- Root hairs are described as thin-walled and cylindrical in shape. This structure is crucial for their function.

3. **Quantity of Root Hairs:**
- Root hairs are present in millions at the tips of the roots. This large number enhances the plant's ability to absorb water and nutrients.

4. **Function of Root Hairs:**
- The primary function of root hairs is the absorption of water and minerals from the soil. They significantly increase the surface area available for absorption.

5. **Mechanism of Absorption:**
- Water and mineral solutes are absorbed by root hairs primarily through the process of diffusion, which is the movement of substances from an area of higher concentration to an area of lower concentration.

6. **Conclusion:**
- Based on the characteristics and functions described, the statement that "root hairs are thin-walled slender extensions of root epidermal cells that are present in millions of number at the root" is true.

**Final Answer:**
- The statement is true.

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