Which epithelium lines the alveoli ?

Explanation

### Step-by-Step Solution:

1. **Understanding the Structure**: The alveoli are tiny air sacs located at the end of the respiratory system in the lungs. They play a crucial role in the exchange of gases (oxygen and carbon dioxide) between the air and the bloodstream.

2. **Identifying the Type of Epithelium**: The walls of the alveoli are lined with a specific type of epithelial tissue. This tissue is essential for the process of gas exchange.

3. **Recognizing the Epithelial Tissue**: The epithelial tissue that lines the alveoli is known as **simple squamous epithelium**. This type of epithelium is characterized by a single layer of flat cells, which allows for efficient diffusion of gases.

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