Modification in the form of leaf spines and stem thorns is observed in

Options

A. watermelon and Australian babool
B. Pumpkin and cacti
C. cacti and Citrus
D. Citrus and cacti

Answer

To solve the question regarding the modification in the form of leaf spines and stem thorns, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Modifications**:
- Plants can modify their leaves, stems, and roots for various functions. In this case, we are focusing on leaf spines and stem thorns.

2. **Identifying Leaf Spines**:
- Leaf spines are modifications of leaves that help in defense against herbivores and reduce water loss. A well-known example of a plant with leaf spines is the cactus.

3. **Identifying Stem Thorns**:
- Stem thorns are modifications of stems that also serve a defensive purpose. They are typically sharp and can deter animals from eating the plant. Citrus plants are known for having thorns on their stems.

4. **Analyzing the Options**:
- A. Watermelon and Australian Baboon: Not relevant to leaf spines and stem thorns.
- B. Pumpkin and Cacti: Pumpkins do not have significant modifications like spines or thorns.
- C. Cacti and Citrus: Cacti have leaf spines, and Citrus has stem thorns.
- D. Citrus and Cacti: This is the same as option C but reversed.

5. **Conclusion**:
- The correct answer is **C. Cacti and Citrus**, as both exhibit the modifications described in the question.

### Final Answer:
C. Cacti and Citrus