Read the assertion and reason carefully to mark the correct option in question.
1. Assertion: Cell is the fundamental structural and functional unit of all living organisms.
Reason: Anything less than a complete structure of a cell does not ensure independent living.

Options

A. If both Assertion & Reason are True & the Reason is a correct explanation of the Assertion.
B. If both Assertion & Reason are True but Reason is not a correct explanation of the Assertion.
C. If Assertion is True but the Reason is False.
D. If both Assertion & Reason are false.

Answer

### Step-by-Step Solution:

1. **Understanding the Assertion**:
- The assertion states that "Cell is the fundamental structural and functional unit of all living organisms."
- This means that every living organism, whether unicellular or multicellular, is made up of cells, which perform all necessary life functions.

2. **Understanding the Reason**:
- The reason states that "Anything less than a complete structure of a cell does not ensure independent living."
- This implies that for an organism to live independently, it must have a complete cell structure capable of performing all life processes.

3. **Connecting Assertion and Reason**:
- The assertion is supported by the reason because if a complete cell structure is necessary for independent living, then it reinforces the idea that cells are the basic units of life.
- Unicellular organisms, which consist of a single cell, demonstrate that a complete cell can carry out all life functions independently.

4. **Evaluating Truthfulness**:
- Both the assertion and the reason are true statements.
- The reason accurately explains why the assertion is valid.

5. **Conclusion**:
- Since both the assertion and the reason are true, and the reason correctly explains the assertion, the correct option is A: "Both assertion and reason are true, and the reason is the correct explanation for the assertion."