Digital ACT Science Practice Question #857

Three geochemists debate the primary trigger of the Cretaceous-Paleogene (K-Pg) boundary mass extinction 66 million years ago. Scientist 1 The extinction was caused solely by the Chicxulub bolide impact. The impact vaporized sulfate-rich anhydrite marine target rocks, injecting over 300 billion tons of sulfur dioxide into the stratosphere. This generated widespread sulfuric acid aerosols, inducing an immediate, severe decade-long impact winter that collapsed oceanic and terrestrial photosynthetic food chains. Scientist 2 The extinction was driven primarily by pulsed flood basalt volcanism in the Deccan Traps. Massive eruptions over a 500,000-year span released thousands of gigatons of CO2 and mercury into the atmosphere, causing repeated catastrophic ocean acidification events. The bolide impact occurred when ecosystems were already terminally destabilized by prolonged volcanic stress. Scientist 3 Neither the impact nor volcanism alone was sufficient. Rather, seismic energy from the Chicxulub impact propagated through the Earth's mantle, concentrating antipodally and dramatically accelerating the eruption rate of the Deccan Traps. Thus, the impact served as an active geodynamic trigger that accelerated hyper-volcanism. Suppose a sediment core from an undisturbed marine basin reveals that deep-sea benthic foraminifera suffered their most abrupt diversity decline less than 50 years after the deposition of the Chicxulub iridium anomaly, with no prior geochemical evidence of ocean acidification. This finding would WEAKEN which scientist’s argument the most?