Pneumatophores show

Options

A. Positively geotropism
B. Negative geotropism (ageotropism)
C. Thigmotropism
D. Negative photoropism.

Answer

**Step-by-Step Solution:**

1. **Understanding Pneumatophores:**
- Pneumatophores are specialized root structures found in certain plants, particularly those that grow in marshy or waterlogged environments. These roots are adapted for gas exchange.

2. **Definition of Geotropism:**
- Geotropism refers to the growth response of a plant to gravity.
- Positive geotropism: Growth towards gravity (downwards).
- Negative geotropism: Growth away from gravity (upwards).

3. **Identifying the Growth Direction of Pneumatophores:**
- Pneumatophores grow upwards, which means they are growing against the force of gravity. This indicates that they exhibit negative geotropism.

4. **Understanding Other Types of Tropisms:**
- Thigmotropism: Growth in response to touch or physical contact with an object.
- Phototropism: Growth in response to light. Negative phototropism would mean growing away from light.

5. **Conclusion:**
- Since pneumatophores grow upwards in a direction opposite to gravity, they exhibit negative geotropism. Therefore, the correct answer is option B: Negative geotropism.

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