Which of the following is a modification of mucosa of alimentary canal.

Options

A. Villi
B. Microvilli
C. Rugae
D. All of these

Answer

To answer the question "Which of the following is a modification of mucosa of the alimentary canal?" we will analyze the options provided: villi, microvilli, rugae, or all of these.

### Step-by-Step Solution:

1. **Understanding Mucosa**: The mucosa is the innermost layer of the alimentary canal. It plays a crucial role in digestion and absorption by providing a surface for nutrient uptake.

2. **Identifying Modifications**: We need to identify which structures are modifications of the mucosa:
- **Villi**: These are finger-like projections found in the small intestine. They increase the surface area for absorption of nutrients.
- **Microvilli**: These are even smaller projections that exist on the epithelial cells of the villi. They further increase the surface area, enhancing absorption.
- **Rugae**: These are folds found in the stomach lining. They allow the stomach to expand and accommodate food, providing elasticity.

3. **Analyzing the Options**:
- **Villi** and **Microvilli** are specifically adaptations that enhance absorption in the small intestine.
- **Rugae** are adaptations that allow the stomach to stretch and are also a modification of the mucosa.

4. **Conclusion**: Since all three structures (villi, microvilli, and rugae) are modifications of the mucosa in different parts of the alimentary canal, the correct answer is **"all of these."**

### Final Answer:
All of these (villi, microvilli, rugae) are modifications of the mucosa of the alimentary canal.

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