Facilitated diffusion therefore allows polar and charged molecules, such as carbohydrates, amino acids, nucleosides, and ions, to cross the plasma membrane. Two classes of proteins that mediate facilitated diffusion are generally distinguished: carrier proteins and channel proteins.
Answer:
B
Explanation:
The plains have large rivers flowing through them. Every living creature or plant that grows requires water, so the answer is B.
Fertilizers are needed by very large farms. It is what makes it possible to grow enough grain to have excesses to sell.
Pesticides are also needed. Insects abound in many sparsely populated areas.
Renewable resources are used, but it is not the answer.
This is because they train extremely hard in order to sustain stamina and endurance so, their bodies don't get the chance to build muscle because they burn more than they consume.