A study by ornithologists examined how urban noise affects bird communication. They hypothesized that birds in loud cities would sing louder to be heard. Recording robins in both quiet forests and noisy city centers, the team found that city robins did not sing louder, but rather sang at a higher pitch. This shift in frequency allowed their songs to cut through the low frequency rumble of traffic.
Which choice best states the main purpose of the text?
To describe how birds adapt their behavior to survive in urban environments
To prove that birds prefer living in cities over forests
To explain why traffic noise is dangerous to human hearing
To argue that robins are the only birds that can live in cities
Correct Answer: A
Choice A is the best answer. The text describes a study on how birds change their song (pitch) to be heard over noise. This is an adaptation to the environment.
Choice B is incorrect. Adaptation doesn't mean preference. Choice C is incorrect. Focus is on birds, not human hearing. Choice D is incorrect. It only discusses robins as the study subject, not as the only bird.