Many models predict that as climates warm, North American tree populations will expand northward into newly suitable habitats. However, forest surveys show that many species, such as the sand post oak (Quercus margaretta) and the slash pine (Pinus elliottii), are exhibiting migration lag—that is, their failure to establish northern populations as predicted. Research suggests that this lag is linked to reduced diversity of essential fungal partners at the northern edges of the trees’ habitats, making it difficult for these trees to successfully expand northward.
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Verbal·Craft and Structure·Text Structure and Purpose
mediumWhich choice best describes the overall structure of the text?
A
It presents a scientific prediction, describes evidence that contradicts that prediction, and then offers an explanation for the contradiction.
B
It describes an environmental problem, discusses several attempted solutions, and then proposes a new solution.
C
It summarizes recent research findings, identifies a gap in current understanding, and then suggests future research to address that gap.
D
It introduces a scientific model, presents several predictions made using data generated by the model, and then provides further support for one prediction over the others.