Why does competition occur in ecosystems? a. competition never happens in ecosystems b. competition occurs only within populations c. competition happens because resources are limited. d. competition happens only over food

Option C. Competition happens because resources are limited.

Explanation:

When resources are limited in an ecosystem, the species compete with each other to come out as best among all.

As per the theory of natural selection, Darwin proposed that it is always the fittest of all that survive. By fittest he means the ones who are capable to compete and come out as the strongest among all to survive in a given ecosystem.

For Example - Male compete among themselves to attract the female. This is known as sexual selection.

Hence, option C is correct.

a. the production of carbon dioxide through the process of photosynthesis

well, that's easy; the answer's c, "it reduces contamination of the water and substrate of the estuary."