Thorns, spines and prickles are

Options

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

Answer

### Step-by-Step Solution:

1. **Understanding the Question**: The question asks about thorns, spines, and prickles, and what category they belong to in terms of plant structures.

2. **Analyzing the Options**: The options provided are:
- A) Respiratory organs
- B) Excretory organs
- C) Organs for reproduction
- D) Defensive organs

3. **Evaluating Each Option**:
- **Option A (Respiratory organs)**: In plants, the primary respiratory organs are the leaves, which contain stomata for gas exchange. Thorns, spines, and prickles do not serve this function. Therefore, this option is incorrect.

- **Option B (Excretory organs)**: Plants do not have specialized excretory organs like animals. They do not need to excrete waste in the same way. Thus, this option is also incorrect.

- **Option C (Organs for reproduction)**: Thorns, spines, and prickles are not involved in reproduction. They do not play a role in the reproductive processes of plants. Hence, this option is incorrect.

- **Option D (Defensive organs)**: Thorns, spines, and prickles serve as protective structures for plants. They help defend against herbivores and other threats. This option correctly categorizes thorns, spines, and prickles.

4. **Conclusion**: After evaluating all the options, it is clear that thorns, spines, and prickles are classified as **defensive organs** in plants. Therefore, the correct answer is **D) Defensive organs**.