The cell theory states that

Options

A. All cells are living
B. All cells have nucleus
C. Cells are fundamental structural units of living organisms
D. Cells reproduce by mitosis and meiosis

Answer

**Step-by-Step Solution:**

1. **Understanding Cell Theory**: The cell theory is a fundamental concept in biology that describes the properties and functions of cells. It was developed in the 19th century by scientists who studied living organisms.

2. **Key Components of Cell Theory**: The cell theory consists of several key statements:
- All living organisms are composed of one or more cells.
- The cell is the basic unit of life.
- All cells arise from pre-existing cells.

3. **Identifying the Correct Statement**: Among the options provided:
- Option A states that all cells are living, which is not entirely accurate as some cells can be dead (like skin cells).
- Option B states that all cells have a nucleus, which is not true for prokaryotic cells (like bacteria).
- Option C states that all cells are the fundamental structural units of living organisms, which aligns with the cell theory.
- Option D states that cells reproduce by mitosis and meiosis, which is not applicable to all cells (e.g., some cells reproduce asexually).

4. **Conclusion**: Based on the analysis of the options, the correct statement that aligns with the cell theory is option C: "All cells are fundamental structural units of living organisms."

5. **Final Answer**: Therefore, the answer is option C.

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