Maybe the paper A has more evidence and more detail than aper b
True - An extensive chain of mountains or mountain ranges, especially the principal mountain system of a continent.
Answer:
The human respiratory system contains the organs that allow us to get the oxygen we need and to remove the waste carbon dioxide we do not need. It contains these parts: two lungs. ... various structures in the chest that allow air to move in and out of the lungs.
There is no answer that is right except for C. Natural Selection.
Genetic Recombination doesn't change gene frequency;nor does migration. (Unless it's local)
Mutation could be the answer, but since mutations are too rare to really power Evolution, the only logical answer is Natural Selection.
