Can someone help me here

1. grass Can survive by itself because it is not dependent on food, it is self-sustaining. and since grass it's not dependent on food it is a producer.

2. and 3. they would all decrease, since the prairie dogs are herbivores they eat basically plants such as grass and if half of the grass is gone then they would have less to eat and therefore decrease.

since ferrets eat prairie dogs, if the prairie dogs population decreases the ferrets would have less to eat and therefore decrease as well.

one of the predators of ferrets are foxes and if the ferrets decrease then the fox would also decrease since it will have less to eat.

4. if we would continue advancing years soon the ferret, prairie dogs and foxes would be no more because if there is less grass they would keep on decreasing over the years until they would be extinct.

a is the best answer your welcome