|will mark as brainlist | what has caused air quality in the united states to improve / get better since the 1950's?

more cars on the road
more industrial production
pollution control devices
more favorable weather patterns

Reforestation or forest reserves.

Explanation:

Trees absorb the carbon from the exhaust of the engines and give oxygen in return

yes its like the dead sea which is full of salt which makes you stay afloat

so yes an egg will float in salt

many other transport proteins, often called pumps, move materials against a concentration gradient. active transport drives molecules across a membrane from a region of lower concentration to a region of higher concentration. this process, shown in figure 5.1, uses transport proteins powered by chemi- cal energy.