To determine the best stage to observe the shape, size, and number of chromosomes, we can analyze the different stages of cell division.
### Step-by-Step Solution:
1. **Understand the Stages of Cell Division**: The cell cycle consists of several stages: interphase, prophase, metaphase, anaphase, and telophase. Each stage has distinct characteristics regarding chromosome visibility.
2. **Interphase**: In this stage, the cell is not dividing, and the chromosomes are in the form of chromatin. They are not condensed, making it difficult to observe their shape, size, and number.
3. **Prophase**: During prophase, chromosomes begin to condense and become visible. However, they are still in the process of condensing and may not be fully distinct or arranged, which makes it challenging to accurately observe their characteristics.
4. **Metaphase**: This is the stage where chromosomes are most condensed and aligned along the metaphase plate. They are fully visible, distinct, and arranged in a way that allows for easy counting and observation of their shape and size. This is the ideal stage for chromosome observation.
5. **Telophase**: In telophase, the chromosomes begin to de-condense back into chromatin as the cell prepares to divide. While they can still be observed, they are not in their most distinct form as in metaphase.
6. **Conclusion**: Based on the analysis, the best stage to observe the shape, size, and number of chromosomes is **metaphase**.
### Final Answer:
The best stage to observe the shape, size, and number of chromosomes is **B) Metaphase**.
