Transport element is

Options

A. potassium
B. calcium
C. manganese
D. magnesium

Answer

**Step-by-Step Solution:**

1. **Understanding Transport Elements**:
- A transport element is defined as an element that plays a crucial role in the transport of ions across cellular membranes, particularly the apical membrane.

2. **Identifying the Options**:
- The question presents four elements: Potassium, Calcium, Manganese, and Magnesium. We need to analyze each to determine which one qualifies as a transport element.

3. **Analyzing Potassium**:
- Potassium (K) is known for its role in transporting sodium (Na) and chloride (Cl) ions across the membrane. This function is essential for maintaining cellular homeostasis and is a key characteristic of a transport element.

4. **Analyzing Calcium**:
- Calcium (Ca) is important for various cellular functions, including cell membrane formation. However, it does not primarily function as a transport element or pump for other ions.

5. **Analyzing Manganese**:
- Manganese (Mn) is a micronutrient that plays a role in photosynthesis but does not function as a transport element for ions across membranes.

6. **Analyzing Magnesium**:
- Magnesium (Mg) is essential for chlorophyll production in plants but, similar to calcium and manganese, it does not serve as a transport element.

7. **Conclusion**:
- Based on the analysis, Potassium is the only element among the options that functions as a transport element by facilitating the movement of sodium and chloride ions across the membrane.

**Final Answer**: The transport element is Potassium.

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