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 will analyze the options provided and identify the correct plants exhibiting these modifications.

### Step-by-Step Solution:

1. **Understanding Plant Modifications**:
- Plants can undergo modifications in their structures for various functions. Leaves, typically designed for photosynthesis, can change form to adapt to environmental conditions.

2. **Identifying Leaf Modifications**:
- In certain plants like cacti, leaves are modified into spines. This adaptation helps reduce water loss through transpiration, which is crucial for survival in arid environments.

3. **Identifying Stem Modifications**:
- Stems can also show modifications. In plants such as citrus and bougainvillea, stems are modified into thorns. These thorns serve as a defense mechanism against herbivores that may feed on the plants.

4. **Analyzing the Options**:
- We need to look for a plant that has leaf spines (like cacti) and another that has stem thorns (like citrus and bougainvillea).

5. **Conclusion**:
- Based on the analysis, the correct answer is option C, which includes cacti for leaf spines and citrus/bougainvillea for stem thorns.

### Final Answer:
The modification in the form of leaf spines and stem thorns is observed in option C (Cacti for leaf spines and Citrus/Bougainvillea for stem thorns).