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.
Answer:
The idea of concentrations and gradients within them is important when understanding the movement of substances across cell membranes. The more particles there are in a certain volume, the more concentrated those particles are. A solution with a low solute concentration has a high water concentration, and a high water potential.
The correct answer is lizard hope this helps