Explanation
Correct answer: C.
Choice C is the best answer because it most effectively uses data from the graph to complete the statement about the researchers’ hypothesis regarding a finding. The text states that the researchers attribute a certain finding about community assembly in fungi and prokaryotes to the fact that fungi have a higher tolerance for environmental pressures than do prokaryotes. This finding, then, would be explained by the fact that fungi better tolerate environmental pressures, which the text defines as including variable and homogeneous selection. According to the graph, the contribution of variable selection to community assembly was nearly 40 percent for fungi but nearly 60 percent for prokaryotes, indicating that variable selection contributed significantly less to fungal community assembly than to prokaryotic community assembly. This finding aligns with the researchers’ hypothesis: because fungi tolerate environmental pressures like variable selection better than prokaryotes do, those pressures play a smaller role in shaping fungal communities than in shaping prokaryotic communities.
Why the other choices are wrong
Choice A
Choice A is incorrect. Although this comparison is supported by the graph, which shows that homogenizing dispersal’s contribution to fungal community assembly was just over 10 percent while variable selection’s contribution was just under 40 percent, this comparison doesn’t illustrate the hypothesis because it involves two factors affecting fungal community assembly. The researchers’ hypothesis specifically concerns a difference between fungi and prokaryotes (namely, fungi’s greater tolerance of environmental pressures), so a comparison that is limited to fungal community assembly doesn’t represent a finding that aligns with this hypothesis.
Choice B
Choice B is incorrect because it mischaracterizes the information in the graph. The graph indicates that the total number of factors that contributed to community assembly was greater for fungi than for prokaryotes: all five factors made nonzero contributions to fungal community assembly, while two factors—homogeneous selection and dispersal limitation—appear not to have contributed to prokaryotic community assembly. In addition, the overall number of factors that influence community assembly isn’t directly relevant to the researchers’ hypothesis, which addresses the effects of higher tolerance of environmental pressures among fungi in comparison to prokaryotes.
Choice D
Choice D is incorrect. Although the graph indicates that homogeneous selection contributed only minimally to fungal community assembly and appears not to have contributed at all to prokaryotic community assembly, this isn’t a finding that the researchers’ hypothesis would account for. The hypothesis concerns a difference between fungi and prokaryotes that is plausibly attributable to fungi’s greater tolerance of environmental pressures, which include homogeneous and variable selection. The finding that one type of environmental pressure contributed negligibly to both groups doesn’t differentiate fungi from prokaryotes and therefore doesn’t illustrate what the hypothesis is meant to explain.