According to cell theory

Options

A. Cells are fundamental structural units of organisms
B. Cells reporduce
C. Cells are living
D. Cell have nuclei

Answer

**Step-by-Step Solution:**

1. **Understanding Cell Theory**: The cell theory is a fundamental concept in biology that describes the properties of cells. It was developed by scientists Matthias Schleiden and Theodor Schwann in the 19th century.

2. **Key Statements of Cell Theory**:
- 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. **Analyzing the Options**:
- **Option A**: "Cells are fundamental structural unit of organisms." - This statement aligns with the cell theory as it emphasizes that cells are the basic building blocks of all living things.
- **Option B**: "Cells reproduce." - While cells can divide and reproduce, this statement is not a direct part of the original cell theory.
- **Option C**: "Cells are living." - This statement is somewhat true, but cell theory does not specifically state that cells are living entities; rather, it focuses on their structural and functional roles.
- **Option D**: "Cells have nuclei." - This is not universally true as prokaryotic cells (like bacteria) do not have a nucleus.

4. **Conclusion**: Based on the analysis, the correct answer according to cell theory is **Option A**: "Cells are fundamental structural unit of organisms."

**Final Answer**: A. Cells are fundamental structural unit of organisms.

---