The control unit of cell is

Options

A. nucleus
B. cell wall
C. cytoplasm
D. all of these

Explanation

**Step-by-Step Solution:**

1. **Identify the Options**: The question asks for the control unit of a cell and provides four options:
- Option 1: Nucleus
- Option 2: Cell wall
- Option 3: Cytoplasm
- Option 4: All of the above

2. **Evaluate Each Option**:
- **Option 1: Nucleus**: The nucleus is known as the control center of the cell. It contains the cell's genetic material (DNA) and is responsible for regulating various cellular activities, including growth, metabolism, and reproduction. Therefore, it is often referred to as the "brain" of the cell.

- **Option 2: Cell Wall**: The cell wall is a rigid outer layer found in plant cells, fungi, and some bacteria. It provides structural support and protection but does not control cellular functions. Thus, it cannot be the control unit of the cell.

- **Option 3: Cytoplasm**: The cytoplasm is the jelly-like substance within the cell membrane where various cellular processes occur. While it is essential for chemical reactions, it does not control these processes. Therefore, it is not the control unit.

- **Option 4: All of the above**: Since only the nucleus functions as the control unit, this option is incorrect.

3. **Conclusion**: Based on the evaluation, the correct answer is **Option 1: Nucleus**. The nucleus is the control unit of the cell because it contains genetic information and regulates cellular activities.