The correct answer is A. The snake population will decrease rapidly and the grass population will increase rapidly.
Step-by-step explanation:
In an ecosystem, different organisms depend on each other for food and nutrients, in the case presented it is expected the rabbits rely on the grass to feed, the snakes hunt the rabbits and finally, the hawks hunt the snakes creating a food chain. This also implies if the population of one organism is affected all the other organisms will also be affected.
According to this, in the case of the population of rabbits decreasing it is expected the grass population increases because there are not enough rabbits to feed on grass and in the same way as there are not enough rabbits for snakes to feed which will decrease the snake population. Thus, the effect, in this case, is a decrease in the snake population and an increase in grass population (Option A).