Assertion: Presence of pneumatophores is a special adaptation of hydrophytes.
Reason: Pneumatophores are positively geotropic shoots that have lenticels and help in gaseous exchange.

Options

A. If both assertion and reason are true and reason is the correct explanation of assertion.
B. If both assertion and reason are true but reason is not the correct explanation of assertion.
C. If assertion is true but reason is false.
D. If both assertion and reason are false.

Answer

To solve the assertion-reason question, we will analyze both the assertion and the reason step by step.

### Step 1: Understand the Assertion
The assertion states: "Presence of pneumatophores is a special adaptation of hydrophytes."
- **Hydrophytes** are plants that thrive in water or very moist conditions.
- **Pneumatophores** are specialized roots that help in gas exchange, typically found in plants that grow in saline or marshy environments, often referred to as halophytes (not hydrophytes).

**Conclusion**: The assertion is incorrect because pneumatophores are adaptations of halophytes, not hydrophytes.

### Step 2: Understand the Reason
The reason states: "Pneumatophores are positively geotropic shoots that have lenticels and help in gaseous exchange."
- **Geotropism** refers to the growth of a plant in response to gravity.
- Pneumatophores are actually **negatively geotropic**, meaning they grow upwards against gravity.
- They do have **lenticels**, which are small openings that facilitate gas exchange.

**Conclusion**: The reason is also incorrect because it incorrectly describes the geotropic nature of pneumatophores.

### Final Conclusion
Both the assertion and the reason are false. Therefore, the correct answer is D: "Both assertion and reason are false."

---