A pet owner dropped some new fish into a pond. Several species of fish lived in the pond, but within a few months, only members of the new species survived. What BEST explains why this happened? A: Too many fish caused an imbalance in the ecosystem, so the food web was affected.

B: All new species have an advantage in an ecosystem.

C: The new species was probably bigger than the other fish in the pond.

D: All of the species were dying out, and the new species was the last to survive.