Elk and bison are both herbivores and engage in exploitative resource competition. Which of the following could be explanations (reasonable hypotheses) as to why both species persist in Yellowstone rather than one of the two species being extirpated due to competitive exclusion.

Use the food web shown in the previous question to help with your answer.

Select all that apply:
a. Competitive exclusion does not occur for two species that share the same trophic level.
b. One of the two species has a much higher ecological efficiency than the other, making competitive exclusion less likely.
c. Their fundamental niches do not completely overlap.
d. Both species are kept well below their carrying capacities by predators.
e. Both species are K-strategists and hence unlikely to be affected by resource competition and competitive exclusion.