The answer is "natural selection is how animals, or plants survive or adapt to their environment".
Reason:
Natural selection is how animals, or<span> plants survive or adapt to their environment this idea came up by Charles Darwin and how he examined the birds beaks which means he came up with the theory of evolution which means that animals evolve to a different type of that species to adapt to there environment with is natural selection.
These molecules need to pass through specific proteins or transmembrane proteins embedded in the cell membrane. A specific type of an integral membrane protein.