Answer:
C: competitive exclusion
Explanation:
The competitive exclusion principle states that organisms living in the same community while competing for the same resources cannot coexist at a constant population rate.
Once some of the species within the community get a slight competitive edge over other species, they become dominant and this might lead to the extinction of the weaker species in the long run.
In the experimental plot, the removal of sea stars provided mussel and barnacle with a competitive advantage over other species within the community (sea stars are predators of mussels and barnacles). This led to the dominance of mussel and barnacle and the eventual extinction of other species within the experimental plot as compared to the control plot.
The correct answer is C.