What do astronomers use to calculate the age of the universe? Select three options.

dark energy
the age of rocks on Earth
the age of the oldest stars
patterns of background radiation
how fast distant galaxies are moving away from us

What is point source pollution of an aquatic ecosystem? a) pollution of freshwater sources b) pollution from many sources that combine into one c) pollution that occurs over a wide area; water that runs off from fields, parking lots, and other land surfaces d) pollution that can easily be identified with a single discharge source, such as an open pipe which drains into a body of water