Task: Question Answering
Input (English): 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?  
 (A) its decomposers (B) its competitors (C) its mutualists (D) its predators
Output (English): B