Body cavities, ducts and tubes are lined by  

Options

A. simple epithelium
B. compound epithelium
C. transitional epithelium
D. pseudo stratified

Answer

### Step-by-Step Solution:

1. **Understanding the Question**: The question asks what type of tissue lines body cavities, ducts, and tubes.

2. **Identifying the Characteristics of the Lining**: Body cavities, ducts, and tubes are typically lined by a single layer of cells. This characteristic is crucial for their function, as it allows for efficient exchange and movement of substances.

3. **Exploring the Types of Epithelium**:
- **Simple Epithelium**: This type consists of a single layer of cells. It is specialized for absorption, secretion, and filtration, making it suitable for lining cavities and tubes.
- **Compound Epithelium**: This consists of multiple layers of cells and primarily serves a protective function, as seen in the skin.
- **Transitional Epithelium**: This type can stretch and is found in areas like the bladder, but it does not line all body cavities and ducts.
- **Pseudo Stratified Epithelium**: This appears to be layered due to varying cell heights but is actually a single layer. It is typically found in the respiratory tract.

4. **Conclusion**: Given that body cavities, ducts, and tubes are lined by a single layer of cells, the correct answer is **simple epithelium**.

### Final Answer:
Body cavities, ducts, and tubes are lined by **simple epithelium**.

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