In the Late 1960s, Robert Paine Conducted Landmark Studies on Diversity

In the late 1960s, Robert Paine conducted landmark studies on diversity in the rocky intertidal zone comparing the species diversity in control plots with diversity in experimental plots from which he removed the top predator, sea stars. After 5 years, 15 species of intertidal invertebrates lived in the control plots, while the experimental plots were dominated by only two species, one mussel and one barnacle. Why did species diversity MOST likely remain high in the presence of a predator?

A) The sea star kept the mussel and barnacle populations low enough to prevent competitive exclusion from occurring.
B) The sea star kept the mussels and barnacles from developing a mutualistic relationship. That, in turn, kept their populations low.
C) The mussels and the barnacles parasitized the sea stars, keeping populations low enough to prevent competitive exclusion from occurring.
D) The sea stars developed a mutualistic relationship with the mussels and barnacles, keeping their populations low and preventing competitive exclusion from happening.