Thorns and spines are -

Options

A. Respiratory organs
B. Excretory organs
C. Organs of offense
D. Defensive organs

Answer

**Step-by-Step Solution:**

1. **Understanding Thorns and Spines:**
- Thorns and spines are specialized structures found in some plants. They serve specific functions that help the plant survive in its environment.

2. **Definition of Thorns:**
- Thorns are sharp, pointed structures that arise from the axillary buds of a plant. They are modifications of the stem, specifically from the nodes of the stem.

3. **Function of Thorns:**
- The primary function of thorns is to act as a defense mechanism. They protect the plant from herbivores and browsing animals that might eat the plant.

4. **Definition of Spines:**
- Spines are modified leaves. In certain plants, such as cacti, the leaves are transformed into spines to minimize water loss and protect the plant.

5. **Function of Spines:**
- Spines serve multiple purposes: they help in reducing water loss in arid environments and can also provide some protection against herbivores. Additionally, they can assist in photosynthesis when they are green.

6. **Examples of Thorns and Spines:**
- Common examples of plants with thorns include Bougainvillea and citrus plants (like lemon). Cacti are well-known for having spines.

7. **Conclusion:**
- Based on the above information, we can conclude that both thorns and spines serve as defensive organs for the plant. Therefore, the correct answer to the question is that thorns and spines are defensive organs.

**Final Answer:**
Thorns and spines are defensive organs.

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