Explanation
Correct answer: D.
Choice D is the best answer. The text describes how a new discovery expands our understanding of Denisovans. The underlined portion describes what we used to believe about Denisovans, which helps the reader understand the significance of the discovery of the molar: it suggests that they lived in more places than we’d previously thought.
Why the other choices are wrong
Choice A
Choice A is incorrect. The underlined portion doesn’t do this. Instead, it explains what we used to believe about Denisovans before the discovery—it doesn’t dismiss the new discovery as false.
Choice B
Choice B is incorrect. The underlined portion doesn’t do this. No term is defined here.
Choice C
Choice C is incorrect. The underlined portion doesn’t do this. The text never tells us what the “goal” of the research was, just what its discovery was.