SAT OwlQuestion bank / Text Structure and Purpose
Many birdwatchers assume that the dawn chorus, the burst of birdsong around sunrise, happens because birds are reclaiming their territories after the night. Territorial defense surely plays a part. But biologist Rafael Duarte points to another factor. In the cool, still air of early morning, sound travels farther and with less distortion than it does later in the day, so a song sung at dawn reaches more listeners.
Which choice best describes the function of the underlined sentence in the text as a whole?
It presents Duarte's main argument about why birds sing at dawn.
It grants that the common explanation has merit before another factor is introduced.
It provides evidence that sound travels farther in the morning.
It rejects the idea that birds sing at dawn to defend their territories against rivals.
Show answer and explanation
Answer: B
The first sentence gives the common explanation, territorial defense. The underlined sentence accepts that it "surely plays a part." Then "But" brings in Duarte's additional factor. So the sentence is a concession before a new point, choice B.
Choice D reverses the sentence. "Surely plays a part" accepts territorial defense; it doesn't reject it.
Why the other choices are wrong
- A. Duarte's argument, about how sound carries in morning air, comes after the underlined sentence.
- C. The evidence about sound traveling farther comes in the last sentence.
- D. The sentence says territorial defense "surely plays a part," which accepts the idea.
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