Question

For decades, agricultural historians assumed that the transition to sedentary farming in the Fertile Crescent was driven solely by sudden climatic drying. Recently, however, archaeologist Arlene Rosen examined phytoliths—microscopic silica structures from ancient plants—at several Epipaleolithic sites. She found that the plants cultivated during the transition thrived in wet, marshy conditions rather than arid ones. This discovery disrupted the established narrative of climate-driven desperation. By demonstrating that early cultivation occurred during a period of ecological abundance, Rosen’s work suggested that the shift to agriculture was a deliberate choice enabled by surplus, rather than a desperate response to starvation.

Based on the passage, which of the following best describes the primary rhetorical function of the sentence "This discovery disrupted the established narrative of climate-driven desperation"?