Why was 1990 an important year regarding air quality? select two options.
the united states took first steps to keep the air clean.
cost-effective ways to reduce pollution were emphasized.
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.

2 and 4

Explanation:

2) Cost-effective ways to reduce pollution were emphasized.

4) Modifications and improvements were made to the Clean Air Act.

I know that this is very late, but good luck!

B, D

Explanation:

copied answer above it was right on the quiz.

one is through turgidity. this occurs before ground tissue ( collenchyma

and sclerenchyma cells) become well

developed to give structural support to the plant as it grows bigger. the xylem

tissue (composed of rigid tissue) of the young

plant render this support and also maintaining osmotic turgidity of the surrounding

plant cells.