In Bougainvillea and Citrus thorns are the modification of …………(i)……..and in cactus spines are a modification of ………..(ii)……….

Options

A. `{:((i),"(ii)"),("Adventitious root","Stem"):}`
B. `{:((i),"(ii)"),("Stem","Leaf"):}`
C. `{:((i),"(ii)"),("Leaf","Stem"):}`
D. `{:((i),"(ii)"),("Stipules","Flower"):}`

Answer

To solve the question regarding the modifications in Bougainvillea, Citrus, and cactus, we can break it down step by step.

### Step-by-Step Solution:

1. **Identify the Plants**: The question mentions two plants, Bougainvillea and Citrus, and one plant, cactus. We need to determine what part of these plants has been modified to form thorns and spines.

2. **Thorns in Bougainvillea and Citrus**:
- Bougainvillea and Citrus both have thorns.
- Thorns are typically modifications of the stem. In these plants, the stems have evolved to form sharp structures that serve as a defense mechanism against herbivores.

3. **Spines in Cactus**:
- Cacti are known for their spines.
- In cacti, these spines are modifications of leaves. The leaves have evolved into spines to reduce water loss and provide protection.

4. **Fill in the Blanks**:
- For the first blank (i), we conclude that thorns in Bougainvillea and Citrus are modifications of the **stem**.
- For the second blank (ii), we conclude that spines in cactus are modifications of the **leaf**.

5. **Final Answer**:
- (i) stem
- (ii) leaf

### Complete Answer:
In Bougainvillea and Citrus, thorns are a modification of **stem** (i), and in cactus, spines are a modification of **leaf** (ii).

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