Extinction points is

Options

A. Atomospheric oxygen where fire gets automatically extinguished
B. Concentration of oxygen below which aerobic respiration stops
C. Light intensity below which plant will not survive
D. Both B and C

Answer

**Step-by-Step Solution:**

1. **Understanding Extinction Points**: The extinction point refers to the minimum concentration of oxygen required for aerobic respiration to occur. Below this concentration, aerobic respiration cannot take place, and anaerobic respiration may occur instead.

2. **Analyzing the Options**:
- **Option A**: Atmospheric oxygen where fire gets automatically extinguished. This suggests a level of oxygen that is insufficient for combustion but may still support aerobic respiration.
- **Option B**: Concentration of oxygen below which aerobic respiration stops. This directly relates to the definition of the extinction point.
- **Option C**: Light intensity below which the plant will not survive. This is unrelated to respiration and therefore not relevant to the extinction point.
- **Option D**: Both B and C. Since option C is incorrect, this option cannot be correct.

3. **Identifying the Correct Answer**:
- Option A is correct because it describes a situation where oxygen levels are too low for combustion but may still allow for aerobic respiration.
- Option B is also correct as it directly relates to the definition of the extinction point.
- Since option C is incorrect, option D is also incorrect.

4. **Conclusion**: The correct answer is **Option A**: Atmospheric oxygen where fire gets automatically extinguished, as it aligns with the concept of the extinction point.

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