Which occurs free in nature?

Options

A. `I_2`
B. Al
C. P
D. O

Explanation

To determine which element occurs free in nature, we can analyze the options provided in the video transcript step by step.

### Step-by-Step Solution:

1. **Identify the Elements**: The elements mentioned in the transcript are iodine (I2), aluminum (Al), phosphorus (P), and oxygen (O2).

2. **Examine Iodine**:
- Iodine is typically found in nature as I2, but it is not abundant in its free state. It is usually extracted from sources like Laminaria digitata (a type of brown algae).
- **Conclusion**: Iodine does not occur free in nature.

3. **Examine Aluminum**:
- Aluminum is primarily found in the form of ores, particularly bauxite (Al2O3·xH2O). It is not found in a free state in nature.
- **Conclusion**: Aluminum does not occur free in nature.

4. **Examine Phosphorus**:
- Phosphorus is extracted from phosphate rock and is not found in a free state in nature.
- **Conclusion**: Phosphorus does not occur free in nature.

5. **Examine Oxygen**:
- Oxygen is found in the atmosphere as O2 and is also present in the ozone layer as O3. It is abundant and occurs freely in nature.
- **Conclusion**: Oxygen occurs free in nature.

6. **Final Answer**: Based on the analysis, the element that occurs free in nature is **Oxygen (O2)**.