Digital SAT Reading and Writing Practice Question #801

Paleontologists long posited that the extraordinary accumulation of undecomposed Lepidodendron plant matter during the Carboniferous period was due to an "evolutionary lag"—specifically, that fungi capable of breaking down the rigid plant polymer lignin had not yet evolved. This hypothesis supposedly explains the massive coal deposits originating from the era. However, recent phylogenomic studies indicate that lignin-degrading Agaricomycetes actually evolved millions of years before the onset of the Carboniferous. Consequently, geochemist Sarah Robinson argues that environmental factors, rather than evolutionary deficits, were the primary driver of coal formation; she posits that the pervasive anoxic (oxygen-depleted) conditions of Carboniferous swamps severely inhibited fungal respiration, halting decomposition regardless of the fungi's metabolic capabilities. Which finding, if true, would most directly support Robinson’s argument?