In the study of cancer, researchers have used different types of cells, different environmental conditions, and different experimental designs. but, all researchers have arrived at the same conclusion. which conclusion is that?
cancer cells stop dividing when they touch.
cancer cells are unspecialized cells.
cancer cells lack contact inhibition.
cancer cells reproduce slowly.

Cancer cells lack contact inhibition meaning meaning that in normal cells when they come in to contact with other cells they stop reproducing only cancer cells do not. They just keep reproducing and growing destroying everything in their path. An example of this is a tumor. 

The answer is atmosphere. there are four spheres of the earth: 1. geosphere (from greek word 'geo' = ground), 2. hydrosphere (from greek word 'hydro' = water), 3. biosphere (from greek word 'bio' = life), and 4. atmosphere (from greek word 'atmo' = air). a magnetosphere is a region of space around astronomical objects controlled by the magnetic field of that object. through the process of elimination, since lightning is present in the air, it can be found in the atmosphere.