According to transpiration-cohesion theory water is pulled upward through the xylem. The cause of the pull is-

Options

A. Guttation
B. Root pressure
C. transpiration
D. condensation

Answer

**Step-by-Step Solution:**

1. **Understanding the Transpiration-Cohesion Theory**: The transpiration-cohesion theory explains how water is transported from the roots to the leaves in plants. It suggests that water is pulled upward through the xylem due to the combined effects of transpiration and the cohesive properties of water molecules.

2. **Identifying the Cause of the Pull**: The question specifically asks for the cause of the pull that allows water to move upward through the xylem. In this context, the pull is primarily due to transpiration, which is the process of water vapor loss from the plant's aerial parts, especially the leaves.

3. **Evaluating the Options**:
- **Option 1: Guttation**: This is the process of water loss in liquid form and occurs when root pressure is high. It is not related to the upward movement of water through the xylem.
- **Option 2: Druck Pressure**: This term seems to be a misspelling or confusion with "turgor pressure," which is related to the pressure within plant cells but does not directly cause the upward pull of water.
- **Option 3: Transpiration**: This is the correct answer, as it creates a negative pressure (tension) in the xylem, pulling water upward from the roots.
- **Option 4: Condensation**: This refers to the change of water vapor into liquid water and does not contribute to the upward movement of water in plants.

4. **Conclusion**: Based on the evaluation of the options, the cause of the pull that allows water to move upward through the xylem according to the transpiration-cohesion theory is **Transpiration**.

**Final Answer**: The cause of the pull is **Transpiration**.

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