Answer:
B
Step-by-step 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.