its decomposers its competitors its mutualists its predators
I gave my students this multiple choice question: The European starling entered North America in the late 1800s. It proved very successful and was able to spread throughout the United States by 1955. The survival and rapid reproduction of starlings most likely limited the population size of which organisms within its habitats?

Only one answer is correct among these 4 choices:
- its decomposers
- its competitors
- its mutualists
- its predators

Could you tell me which one is correct?

its competitors