Answer:
c. A piece of mesh, keeping some things out and letting some things in
Explanation:
The cell membrane of a cell is described as "selectively permeable". Permeable means things can go through it, but the word selectively is the important part. It lets things in, but it also keeps things out. This way it can regulate the different things that go in and out of the cell. It allows certain molecules that provide the cell nourishment and other things that help it function, and at the same time, it allows waste to move out of the cell. Not all needed molecules can go through the "mesh-like" membrane, that why some of them need help.
A total solar eclipse is seen when the observer is in the moons penumbra
DDT affects the environment negatively. In the past, DDT was known to not cause harm in human because the molecules of DDT are not absorbed by the human skin. But new studies suggested that humans actually have DDT on their bodies and it stays on the liver, kidneys and others. DDT is being used in agriculture; it would be drained into the bodies of water where fishes live, the fishes will then be eaten by birds, humans and other predators. This flow of contamination shows the interdependence of life on earth.
