Question

since the dawn of the industrial revolution, human activity has disrupted the delicate balance of the nitrogen cycle. cars and factories emit nitrogen oxides, which mix with other tiny solids and liquid droplets in the air to form particulate matter. particulate matter is one of the most harmful airborne pollutants, and long - term exposure can result in serious health problems. when those same nitrogen oxides react with water, oxygen, and the sulfur compounds released by the burning of fossil fuels, it can lead to acid rain. this type of precipitation is especially damaging to plants, soil, and historic buildings. but excess nitrogen doesnt just affect our atmosphere. the widespread use of nitrogen - based fertilizers in commercial farming strips soil of other critical nutrients and minerals that plants need to grow. fertilizer runoff frequently ends up in our waterways, where the surplus nitrogen feeds toxic algae blooms. too much algae in a body of water can leave other species without adequate oxygen and light, creating dead zones where marine life is unable to thrive. today, there are more than 400 dead zones around the world, including one in the gulf of mexico that covers over 3,000 square miles. particulate matter is ______. choose one option a made up solely of nitrogen oxides b a dangerous combination of airborne particles c the rapid growth of algae in a body of water d the runoff from nitrogen - based fertilizers

Explanation:

• Option A: The text says nitrogen oxides mix with other solids and liquid droplets to form particulate matter, so it's not solely nitrogen oxides. Eliminate A.
• Option B: The passage states "nitrogen oxides, which mix with other tiny solids and liquid droplets in the air to form particulate matter" and calls it a harmful airborne pollutant. This matches "a dangerous combination of airborne particles".
• Option C: Algae growth is related to fertilizer runoff and excess nitrogen in water, not particulate matter. Eliminate C.
• Option D: Fertilizer runoff is a separate issue leading to algae blooms, not what particulate matter is. Eliminate D.

Answer:

B. a dangerous combination of airborne particles