Sap wood/Heart wood is dark brown in colour.

Answer

### Step-by-Step Solution:

1. **Understanding the Terms**:
- **Sapwood**: This is the outer, living part of the secondary xylem in a tree. It is responsible for the transport of water and nutrients from the roots to the leaves.
- **Heartwood**: This is the inner part of the secondary xylem that is no longer involved in water transport. It is typically denser and provides structural support to the tree.

2. **Color Comparison**:
- **Sapwood Color**: Sapwood is generally lighter in color compared to heartwood. It appears more yellowish or pale.
- **Heartwood Color**: Heartwood is known for its darker coloration, often appearing dark brown or reddish-brown due to the accumulation of various compounds and the absence of living cells.

3. **Conclusion**:
- Based on the color characteristics, heartwood is the part of the wood that is dark brown in color, while sapwood is lighter. Therefore, the correct answer to the question is **heartwood**.

### Final Answer:
Heartwood is dark brown in color.

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