The process of zone refining is used for `:`

Options

A. `2P_(1)`
B. `3P_(1)`
C. `3.5P_(1)`
D. less than `2P_(1)`

Explanation

**Step-by-Step Solution:**

1. **Understanding Zone Refining**: Zone refining is a technique used to purify materials, particularly metals and semiconductors. The process involves melting a small region of the material and moving this molten zone along the length of the solid material.

2. **Purpose of Zone Refining**: The primary purpose of zone refining is to achieve high purity levels in materials. It is particularly effective in removing impurities from semiconductor materials.

3. **Application in Semiconductors**: Zone refining is especially important in the semiconductor industry, where the purity of materials like silicon, germanium, and gallium is crucial for the performance of electronic devices.

4. **Mechanism of Impurity Removal**: As the molten zone moves through the solid material, impurities tend to concentrate in the molten phase. This allows for the separation of impurities from the desired pure material as the molten zone moves and solidifies behind it.

5. **Conclusion**: Therefore, the process of zone refining is used for obtaining the purest form of elements, particularly in the semiconductor industry for materials like silicon, germanium, and gallium.

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