A scientist observes that when she opens the back door of her house to let her cat out, the songs of a certain species of bird abruptly change. She wants to follow up on her observations with an informal experiment. Which of the following is the best hypothesis for explaining the birds’ song changes?A. The bird species switches from song to warning call whenever it sees a potential predator. B. The bird species has a variety of songs that it sings, regardless o what is happening in its environment. C. The scientist is mistaken and the songs do not change. D. The bird species switches from song to warning call whenever it sees a potential predator.