The correct answer is: B. Smog
Smog is a mixture of air pollutants that form when sunlight reacts with nitrogen oxides and hydrocarbons from vehicle exhaust, power plants, and industrial emissions. Smog can cause respiratory problems, heart disease, and cancer.
Global warming is the long-term heating of Earth’s climate system observed since the pre-industrial period (between 1850 and 1900) due to human activities, primarily fossil fuel burning, which increases heat-trapping greenhouse gas levels in Earth’s atmosphere. The term is frequently used interchangeably with the term climate change, though the latter refers to both human- and naturally produced warming and the effects it has on our planet. It is most commonly measured as the average increase in Earth’s global surface temperature.
The ozone hole is a thinning of Earth’s ozone layer in the stratosphere, which absorbs most of the Sun’s ultraviolet radiation. It was first observed in 1985 over Antarctica, and has since been observed over other parts of the Earth. The main cause of the ozone hole is the release of chlorofluorocarbons (CFCs) into the atmosphere. CFCs are chemicals that were once widely used in refrigerators, air conditioners, and aerosol cans. They are now banned in most countries, but the ozone hole is still a problem.
Acid rain is a form of precipitation that is more acidic than normal rain. It is caused by emissions of sulfur dioxide and nitrogen oxides from burning fossil fuels. These emissions react with water vapor in the atmosphere to form sulfuric acid and nitric acid. Acid rain can damage forests, lakes, and crops. It can also corrode buildings and infrastructure.