SAT Inferences Question

Periods of subfreezing temperatures in Alaska have been growing shorter as a result of climate changes, potentially enabling increased carbon dioxide (CO₂) absorption through greater productivity of sidebells wintergreen (Orthilia secunda) plants and other vegetation, but also potentially enabling increased CO₂ output through greater heterotrophic respiration (CO₂ generated by the activity of soil microorganisms). Hydrologist Yonghong Yi and her colleagues developed a model incorporating numerous inputs — years of soil moisture and snow cover data among them — to evaluate the effects of climate changes on the CO₂ balance in Alaska, concluding that net CO₂ is likely to increase if seasonal snow cover arrives earlier relative to the onset of soil surface freezing. Which finding, if true, would most directly support the researchers' conclusion?