The options are missing from the question,below are the missing options;
a. Trophic cascade
b. Primary succession
c. Autograph
d. Eutrophication
e. Pioneer community
The correct answer to the question is option A.
TROPHIC CASCADE.
Trophic Cascade occurs when there is a series of significant difference/changes in the population size of organisms in the tropic level of an ecosystem.this change in trophic level occurs in a food chain and as a result of predators being in high trophic levels, they use the opportunity to indirectly promote the population of the organisms in the low trophic levels,they do so by ensuring that species that are at intermediate trophic levels are are in close watch or check.
This corresponds with the viral video of of how wolves change rivers featuring
the reintroductionn of wolves to Yellowstone after a 70 year absence which led to multiple changes in the biodiversity and ecology of the park.