Particulate matter in the air decreases life expectancy according to many researchers. Pollutants such as ozone irritate people's breathing, trigger asthma symptoms and cause lung and heart diseases. Exposure to environmental tobacco smoke causes many severe respiratory health problems such as asthma and lung cancer.
A corrosive gas that comes primarily from combustion of fossil fuels such as coal and oil -respiratory irritant, effects plant tissues too -combustion of plants and animals bring SO2 to air- fuels combusted sulfur combines with oxygen or volcanic eruptions or forest fires
i think it is D, she has already constructed the hypothesis and needs is performing the experiment. there is not much of an observation stage because she is looking at a distant end result in a set time frame.
