Assertion : A bigger organism has a large number of cells than a smaller one
Reason : The size of cell is related to the size of the organisms

Options

A. If both assertion and reason are true and reason is the correct explanation of assertion
B. If both assertion and reason are true but reason is not the correct explanation of assertion
C. If assertion is true but reason is false
D. If both assertion and reason are false

Answer

### Step-by-Step Solution:

1. **Understanding the Assertion**:
- The assertion states that "A bigger organism has a large number of cells than a smaller one."
- This statement is true because larger organisms are typically multicellular, meaning they consist of many cells.

2. **Understanding the Reason**:
- The reason provided is "The size of the cell is related to the size of the organisms."
- This statement is false. While larger organisms have more cells, the size of individual cells does not necessarily correlate with the overall size of the organism. For example, some unicellular organisms can be quite large, and the size of cells can vary independently of the organism's size.

3. **Conclusion**:
- Since the assertion is true and the reason is false, the correct answer to the question is that the assertion is true, but the reason is false.

### Final Answer:
- The assertion is true, but the reason is false.