Formation of diffusion boundary is the chief function of  

Options

A. Tile like cells
B. Cube like cells
C. Pillar like cells
D. All the above

Answer

### Step-by-Step Solution:

1. **Understanding the Question**: The question asks about the formation of a diffusion boundary and which type of cells is primarily responsible for this function.

2. **Identifying Key Concepts**:
- A diffusion boundary is crucial for processes like gas exchange and nutrient absorption.
- Such boundaries are typically found in structures where rapid diffusion is necessary, such as blood vessels and alveoli in the lungs.

3. **Analyzing the Options**:
- **Tile-like cells**: These are representative of simple squamous epithelium, which is flat and allows for efficient diffusion.
- **Cube-like cells**: These refer to cuboidal epithelium, which is not primarily involved in forming diffusion boundaries.
- **Pillar-like cells**: These are columnar cells, which also do not serve the primary function of forming diffusion boundaries.
- **All of the above**: This option suggests that all types of cells contribute equally to the formation of diffusion boundaries, which is incorrect.

4. **Conclusion**: The correct answer is tile-like cells, as they are part of the simple squamous epithelium that forms diffusion boundaries effectively.

### Final Answer:
The formation of diffusion boundary is the chief function of **tile-like cells**.

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