The tissue whose cells acts like a diffusion boundary is :

Options

A. Simple Cuboidal epithelium
B. Simple Columnar epithelium
C. Simple Squamous epithelium
D. All of the above

Answer

To solve the question "The tissue whose cells act like a diffusion boundary is:", we will analyze the options provided and determine which tissue type is most suitable for this function.

### Step-by-Step Solution:

1. **Identify the Options**: The options given are:
- A) Simple cuboidal epithelium
- B) Simple columnar epithelium
- C) Simple squamous epithelium
- D) All of the above

2. **Understand the Function of Each Tissue**:
- **Simple Cuboidal Epithelium**: This type of epithelium consists of a single layer of cube-shaped cells. It is primarily involved in secretion and absorption, commonly found in glands and kidney tubules.
- **Simple Columnar Epithelium**: This epithelium is made up of a single layer of tall, slender cells. It is found in the lining of the stomach and intestines and is mainly involved in secretion and absorption.
- **Simple Squamous Epithelium**: This tissue consists of a single layer of flattened cells. It is found in areas where rapid diffusion or filtration is necessary, such as in the walls of blood vessels (endothelium) and the air sacs of the lungs (alveoli).

3. **Determine the Tissue Acting as a Diffusion Boundary**:
- The key function of a diffusion boundary is to allow for the efficient exchange of gases, nutrients, and waste products. Simple squamous epithelium, due to its thin and flat structure, provides a minimal barrier for diffusion, making it ideal for this function.

4. **Conclusion**:
- Based on the analysis, the tissue whose cells act like a diffusion boundary is **C) Simple squamous epithelium**.

### Final Answer:
**C) Simple squamous epithelium**