Schleiden and Schwann proposed

Options

A. Protoplasm as the physical basisi of life
B. Cell theory
C. Theory of cell lineage
D. Nucleus functions as control centre of cell

Answer

**Step-by-Step Solution:**

1. **Identify the Scientists**: The question refers to two prominent scientists, Schleiden and Schwann. It is important to recognize their contributions to cell biology.

2. **Understand Their Contribution**: Schleiden and Schwann are known for formulating the cell theory. This theory is fundamental in biology and outlines the significance of cells in living organisms.

3. **Define Cell Theory**: The cell theory states that:
- 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.

4. **Differentiate Other Options**:
- Option A (Protoplasm as the physical basis of life) was proposed by another scientist, not Schleiden and Schwann.
- Option C (Theory of cell linkage) was proposed by Dutrochet.
- Option D (Nucleus formation as control center of cell) was proposed by Robert Brown.

5. **Conclude with the Correct Answer**: Based on the contributions of Schleiden and Schwann, the correct answer to the question is option B: Cell theory.

**Final Answer**: The correct answer is **B. Cell theory**.

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