Answer:In the upper thermosphere, atomic oxygen (O), atomic nitrogen (N), and helium (He) are the main components of air. ... Earth's ionosphere, composed of several regions of such ionized particles in the atmosphere, overlaps with and shares the same space with the electrically neutral thermosphere. I hope that helps if not let me know and ill try my best to explain it better:)
I think the answer is "viruses can only multiply within a living cell." the other ones don't really sound right. but i'm not absolutely sure.
Cell Size and Scale, an elegant and deceptively simple interactive from the University of Utah's Genetic Science Learning Center, enables you to compare the sizes of various really small things. The interactive is available free on the Internet and works on desktop computers, smart phones, and tablets.
Selective selection,since being smaller is an advantage the rabbits got smaller similar to evolution
