Zebra Mussels Were Introduced into Lake St

Zebra mussels were introduced into Lake St. Clair around 1988. The table lists the population densities (in grams dry weight per square meter of lake bottom) of native unionid mussels and exotic zebra mussels in the lake before and after this introduction. Both groups feed by filtering small particles from the water. Based on the information given, which of the following BEST describes the likely relationship between zebra mussels and unionids?

A) Unionids exert a density-dependent control on zebra mussel populations.
B) Unionids exert a density-independent control on zebra mussel populations.
C) Zebra mussels exert a density-dependent control on unionid populations.
D) Zebra mussels exert a density-independent control on unionid populations.
E) Zebra mussels and unionids have no effect on each other.