A single cell performing all physiological activites is observed in

Options

A. Monera
B. Protista
C. Yeast (fungi)
D. All the above

Answer

To answer the question "A single cell performing all physiological activities is observed in," we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Question**:
- The question asks about a single cell that can perform all physiological activities. This implies we are looking for unicellular organisms.

2. **Identifying Unicellular Organisms**:
- Unicellular organisms are those that consist of a single cell and can perform all necessary life functions within that one cell.

3. **Analyzing the Options**:
- The options provided are:
- A) Monera
- B) Protista
- C) Yeast
- D) All of the above

4. **Exploring Each Option**:
- **Monera**: This kingdom includes prokaryotic organisms, which are unicellular and perform all physiological activities within a single cell (e.g., bacteria).
- **Protista**: This kingdom primarily consists of unicellular eukaryotic organisms, such as protozoa and some algae, which also perform all life functions within a single cell.
- **Yeast**: Yeasts are unicellular fungi (eukaryotic) that carry out all physiological processes in a single cell.

5. **Conclusion**:
- Since all three options (Monera, Protista, and Yeast) consist of unicellular organisms that perform all physiological activities within a single cell, the correct answer is:
- **D) All of the above**.

### Final Answer:
The answer is **D) All of the above**.