Please help! I will give x Why was 1990 an important year regarding air quality?

The United States took first steps to keep the air clean.
The United States created the Environmental Protection Agency.
Modifications and improvements were made to the Clean Air Act.
Funding was established under the Clean Air Act to study air pollution.

Nucleic acid certain protein cell membranes certain carbohydrates

Choose one animal (cheetas) and research on the internet what has contributed to this animal becoming "endangered" or "threatened." what animal you have chosen? how long has the animal been endangered or threatened? what has contributed to this animal’s endangered or threatened status? why is it important to save this animal from extinction? after researching and gathering facts, write a 350-word letter from the point of view of an animal rights' activist. be sure to include at least five facts that you learned from your research.

Why is the theory of evolution important? it disproves all other theories about how life began. it provides a topic for debate. it is a unifying concept in biology. it explains how life began. i know for sure, it is not "it is a unifying concept in biology."