Which cactus plant is modified into part of the spine?

Options

A. Stem
B. Roots
C. Leaves
D. Branches

Answer

### Step-by-Step Solution:

1. **Understanding the Structure of Cactus**: Cacti are unique plants that have adapted to survive in arid environments. They have specialized structures that help them conserve water and protect themselves from herbivores.

2. **Identifying the Modified Parts**: In cacti, various parts of the plant have undergone modifications. The question specifically asks which part is modified into spines.

3. **Options Analysis**:
- **Stem**: In cacti, the stem is typically thick and fleshy, serving as the main water storage organ.
- **Root**: The roots are primarily for anchoring and absorbing water and nutrients from the soil.
- **Leaves**: In most plants, leaves are responsible for photosynthesis. However, in cacti, leaves are modified.
- **Branches**: While branches can be modified, they do not typically turn into spines.

4. **Correct Answer**: The correct answer is **leaves**. In cacti, the leaves have evolved into spines. This modification serves two main purposes: it reduces water loss through transpiration and provides protection against animals that might eat the cactus.

5. **Conclusion**: Therefore, the part of the cactus that is modified into spines is the **leaves**.

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