I think the answer to this is D.
It is the same as creating more pests or setting up dominant species which upset the ecological food pyramid leading to decimation of trophic levels or predators and energy cycling. Fishes feed on microscopic algae and animals the primary base of the food chain in water, if they are not checked they will choke the rivers and oceans causing toxic waters. Fish feed to contain them, in the process they grow and increase in numbers but their population is checked by bigger fishes and so on till it reaches a top predator which is usually a large animal.
Answer:
Natural selection.
Explanation:
Imagine in the beginning there was a single species of bird. Naturally, this bird had to expand to the rest of the world, and was distanced as the continents drifted off. But this bird had to cope with various climates and environments. So the bird would gradually mutate over time. The bird in the jungles of central america would develop different colors and a shaped beak, and would better help it survive. This led to being the new normal for birds of this area. It would evolve to cover all the surviving birds in the region, until it is so drastically changed then it is a new species. There are so many different environments, each with its own challenges to overcome, so so many different bird evolve to survive them.
<span>Luca Cavalli-Sforza is a geneticist who hypothesized that the skin-color change came late because previous people had complete vitamin D access to the foods that they are eating. But the moment they started farming, the main vitamin sources are reduced, making a larger gain of having light skin.</span>
