Root hairs are

Options

A. Endogenous
B. Multicellular
C. Protected by root cap
D. Unicellular and short lived

Answer

### Step-by-Step Solution:

1. **Understanding Root Hairs**:
- Root hairs are extensions of root epidermal cells that increase the surface area for absorption of water and nutrients from the soil.

2. **Analyzing the Options**:
- **Endogenous**: This term means originating from within. Root hairs are not formed from within the root; they grow from the outer layer (epidermis) of the root, making this option incorrect.
- **Multicellular**: Root hairs are actually unicellular structures. Each root hair is formed from a single epidermal cell, so this option is also incorrect.
- **Protected by Root Cap**: The root cap is a structure that protects the growing tip of the root as it penetrates the soil. It does not protect root hairs; rather, root hairs grow behind the root cap, making this option incorrect.
- **Unicellular**: As mentioned, root hairs are indeed unicellular, which is a correct statement.
- **Short-lived**: Root hairs have a short lifespan; they typically live for a few days to a week before they die off and are replaced by new ones. This statement is also correct.

3. **Conclusion**:
- Based on the analysis of the options, the correct characteristics of root hairs are that they are **unicellular** and **short-lived**.

### Final Answer:
Root hairs are **unicellular** and **short-lived**.

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