Which of the following is a source of particulate matter in the air?

• A. Nitrogen fixation by bacteria
• B. Water evaporation from lakes
• C. Photosynthesis by plants
• D. Burning of fossil fuels

Answer: (D)

Verified step by step guidance

1. Understand the concept of particulate matter: Particulate matter refers to tiny solid or liquid particles suspended in the air, which can originate from natural or human-made sources. These particles can include dust, soot, smoke, and other pollutants.
2. Analyze the options provided: Nitrogen fixation by bacteria, water evaporation from lakes, and photosynthesis by plants are natural processes that do not produce particulate matter. These processes involve chemical or biological activities that do not release solid or liquid particles into the air.
3. Focus on the correct answer: Burning of fossil fuels is a human-made activity that releases particulate matter into the air. Fossil fuels such as coal, oil, and natural gas, when burned, produce smoke and soot, which are examples of particulate matter.
4. Relate the burning of fossil fuels to air pollution: The combustion process generates particulate matter along with other pollutants like carbon dioxide (CO₂), sulfur dioxide (SO₂), and nitrogen oxides (NOₓ). These particles contribute to air pollution and can have harmful effects on human health and the environment.
5. Conclude the reasoning: Based on the analysis, the correct answer is 'Burning of fossil fuels,' as it is the only option that directly produces particulate matter in the air.