The most harmful air pollutant produced by automobiles is

Options

A. `HNO_(2)`
B. NO
C. `SO_(2)`
D. CO

Answer

**Step-by-Step Solution:**

1. **Understanding Automobiles**:
- Automobiles are vehicles used for transportation, which include cars, buses, trucks, and motorcycles. They are a significant source of air pollution.

2. **Identifying Types of Pollution**:
- Automobiles contribute to two main types of pollution: air pollution and noise pollution. In this context, we focus on air pollution.

3. **Recognizing Common Air Pollutants from Automobiles**:
- The primary air pollutants emitted by automobiles include hydrocarbons, carbon monoxide, and nitrogen oxides.

4. **Evaluating the Harmfulness of Each Pollutant**:
- While hydrocarbons and nitrogen oxides are harmful, carbon monoxide (CO) is particularly dangerous. It is a colorless, odorless gas that can have severe health effects.

5. **Understanding the Effects of Carbon Monoxide**:
- Carbon monoxide binds with hemoglobin in the blood more effectively than oxygen, reducing the amount of oxygen transported throughout the body. This can lead to serious health issues such as unconsciousness, brain damage, or even death.

6. **Conclusion**:
- Based on the information gathered, the most harmful air pollutant produced by automobiles is carbon monoxide.

**Final Answer**: The most harmful air pollutant produced by automobiles is carbon monoxide.

---