Heart wood helps in

Options

A. mechanical support
B. circulation
C. ascent of sap
D. translocation of food

Answer

### Step-by-Step Solution:

1. **Understanding Heartwood**: Heartwood is the central, non-living part of a tree trunk that is formed from the older xylem. It is typically darker in color and denser than the outer layers of wood.

2. **Composition of Heartwood**: In older trees, the heartwood cells become filled with substances such as resins and tannins. These substances are produced by the adjacent living cells and contribute to the heartwood's durability and hardness.

3. **Function of Heartwood**: The primary function of heartwood is to provide mechanical support to the tree. It does not participate in the conduction of water or nutrients, as it is composed of non-functional xylem.

4. **Distinguishing Heartwood from Sapwood**: Unlike heartwood, sapwood (also known as alburnum) is the outer layer of the xylem that is involved in the conduction of water and minerals. Sapwood is typically lighter in color and more porous.

5. **Evaluating the Options**: The options given are:
- A) Mechanical support
- B) Circulation
- C) Ascent of sap
- D) Translocation of food

Based on the understanding that heartwood provides mechanical support and does not conduct water or nutrients, the correct answer is **A) Mechanical support**.