Interrelatedness can be observed in the ecosystem of Yellowtone, in which species interaction is key to maintaining a balance in the ecosystem. Option B represents a correct example of interrelatedness.
Wolves prey on elk, thereby reducing the population of elk they browse on willows. The control of the population of elk would lead to the increase of willows as well as allow for their massive growth. These willows are very important to beavers. More willows would mean more beavers. Beavers gnaw on huge willows which they use in constructing dams to slow down water flow. Beavers do not really love rivers that flow fast, and so rely on willows to make dams.
La Niña follows after an El Niño. Its sea surface temperature will be lower than the natural one by 3-5 degree Celcius which tells us that it is cooler than the average temperature. It is the positive state of the El Niño. It really disturbs the natural weather patterns which could result to extreme storms.
