Answer:
It has gotten worse.
Explanation:
In the past 30 years, air quality in the United States has declined almost exponentially. Pollution is the main reason for the declination of air quality in the United States, but there are different kinds of pollution, including light pollution, noise pollution, air pollution, water pollution, etc. Air pollution can be caused by primary or secondary pollutants. Primary pollutants include carbon, nitrogen, and sulfur oxides as well as just general particles in the air. Secondary pollutants are formed when pollutants are exposed to sunlight via chemical reactions.
Pollution :) Since Abiotic means non living.
Bacteria: Living
Food (worms or smaller fish): Living
Predators: Living
Pollution (dirt, trash, or other stuff): Non Living
When a stem cell divides, each new cell can either stay a stem cell or become a specialized cell, such as a muscle cell, a red blood cell, or a brain cell.
B) Flu is easily transmitted from person to person.
If there is a very big population density, it means more people are present in a small amount of space. Thus they will come into contact more often and the virus is likelier to spread more rapidly.