Root hairs are

Options

A. positively geotropic
B. negatively geotropic
C. plagiogeotropic
D. ageotropic

Answer

**Step-by-Step Solution:**

1. **Understanding Root Hairs**: Root hairs are small, hair-like structures that extend from the root of a plant. Their primary function is to increase the surface area for water and nutrient absorption from the soil.

2. **Analyzing the Options**:
- **Option A: Positively Geotropic**: This implies that the roots grow towards gravity. While roots do exhibit positive geotropism, root hairs themselves do not exhibit this characteristic as they are not responsible for the overall direction of root growth.

- **Option B: Negatively Geotropic**: This suggests that the roots grow against gravity. This is incorrect for root hairs, as they are part of the root structure that grows downward, not against gravity.

- **Option C: Plagiogeotropic**: This term refers to growth at an oblique angle, typically seen in lateral branches or roots. Root hairs do not grow at an angle; they grow directly from the root.

- **Option D: Ageotropic**: This means that the growth is not influenced by gravity. Root hairs can be considered ageotropic because they extend in various directions to maximize nutrient and water uptake, independent of gravitational pull.

3. **Conclusion**: After evaluating all options, the correct answer is that root hairs are **Ageotropic** (Option D). They grow in a manner that is not influenced by gravity, focusing instead on maximizing absorption.