How does adaptation affect health of an ecosystem

What could potentially occur is a species establishes an adaptation in which the population of said species could increase, thus destabilizing the natural balance of consumers of all trophic levels within that ecosystem. Ex: A species of deer acquires a resistance to disease and infection via ticks, their population would naturally increase, subsequently increasing the amount of predators (since the predators' food source would increase) as well as a decrease in the food source of the deer species (since the deer food source would not be able to keep up with the increase in deer population).

The correct answer is b