Two non-metallic oxides A and B are produced by burning of fossil fuels. A pollutes both air and water. B does not cause water pollution and its presence in water is essential. It causes air pollution. Identify A and B.

Options

A. `NO_2, SO_2`
B. `SO_2, CO`
C. `SO_2, CO_2`
D. `CO_2, NO_2`

Explanation

To solve the problem, we need to identify two non-metallic oxides A and B produced by burning fossil fuels, based on the clues given about their effects on air and water.

### Step-by-Step Solution:

1. **Understanding the Context**:
- We are looking for two non-metallic oxides produced from burning fossil fuels.
- We know that one oxide (A) pollutes both air and water, while the other oxide (B) causes air pollution but is essential in water and does not pollute it.

2. **Identifying Oxide A**:
- Since A pollutes both air and water, we can consider common non-metallic oxides that are known to cause pollution.
- Two common candidates are sulfur dioxide (SO₂) and nitrogen dioxide (NO₂). Both are produced from burning fossil fuels and contribute to air pollution and acid rain, which can pollute water.

3. **Identifying Oxide B**:
- Oxide B does not cause water pollution but is essential in water. The only non-metallic oxide that fits this description is carbon dioxide (CO₂).
- CO₂ is essential for aquatic plants for photosynthesis and does not directly pollute water, although it contributes to air pollution.

4. **Final Identification**:
- Based on the analysis:
- A is either SO₂ or NO₂ (both cause air and water pollution).
- B is CO₂ (essential in water and causes air pollution).

5. **Conclusion**:
- Therefore, we can conclude that:
- A = SO₂ or NO₂ (both are valid answers for A)
- B = CO₂

### Answer:
- A: SO₂ or NO₂ (either can be correct)
- B: CO₂