An ability to resist a pulling force of water (tensile strength) is depends upon

Answer

**Step-by-Step Solution:**

1. **Understanding Tensile Strength**: Tensile strength refers to the ability of a substance (in this case, water) to resist being pulled apart. In plants, this is particularly important for the movement of water through the xylem.

2. **Identifying Key Forces**: The tensile strength of water is influenced by three main forces:
- **Cohesive Forces**: These are the attractive forces between similar molecules. In the context of water, this means the attraction between water molecules themselves. This cohesion allows water to form a continuous column in the xylem vessels, which is essential for water transport in plants.

- **Adhesive Forces**: These forces are the attractive forces between different types of molecules. For instance, this refers to the attraction between water molecules and the polar surfaces of the xylem walls. This adhesion helps water to cling to the walls of the xylem vessels, aiding in its upward movement against gravity.

- **Surface Tension**: This is a phenomenon that occurs due to cohesive forces at the surface of a liquid. In water, surface tension results from the strong attraction between water molecules at the surface, which creates a sort of 'skin' that can resist external force. This property is crucial for the formation of water droplets and also plays a role in the movement of water in plants.

3. **Conclusion**: Therefore, the ability of water to resist pulling forces (tensile strength) is dependent on the combination of cohesive forces, adhesive forces, and surface tension. Each of these forces contributes to the overall strength and stability of the water column in the plant's vascular system.

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