What must nitrogen compounds be changed to before they can be absorbed by plants? A. Nitrites B. Ammonia C. Ammonium D. Nitrates

it would be f

explanation:

there are so many examples for that in different areas, like biology experiment carried out in our lab recently.

here's one link:

the water is warmed up by the sun and then it evaporates into the atmosphere. the sunlight warms the water by its heat. water is then cooled down and condensation takes place. the water then finally returns back to the earth by the process of precipitation in the form of rain or ice.

explanation:

the wetland preservation movement began in the u.s. in earnest with the clean water act (cwa) of 1972. although not specifically written to protect wetlands, the cwa is comprised of a series of regulations designed to prevent pollutants from contaminating u.s. waters.