Question

### Late Devonian Mass Extinction

Introduction
The Late Devonian mass extinction (approximately $372$ million years ago) was characterized by widespread marine anoxia (depletion of oxygen in ocean water) that devastated marine ecosystems. Two students discuss the primary cause of this extinction event.

Student 1
The extinction was triggered by the rapid evolution and expansion of deep-rooted vascular land plants. As these plants spread, their roots accelerated the chemical weathering of silicate rocks on land. This process consumed vast amounts of atmospheric carbon dioxide ($CO_2$), causing a significant drawdown of greenhouse gases that led to rapid global cooling and continental glaciation. Furthermore, the accelerated weathering washed massive nutrients (such as phosphorus) into the oceans. This caused widespread eutrophication (algal blooms), which depleted dissolved oxygen in the water as the algae decayed, leading to marine anoxia.

Student 2
The extinction was caused by large-scale volcanic eruptions of the Viluy Large Igneous Province (LIP). These massive submarine eruptions released enormous quantities of carbon dioxide ($CO_2$) and sulfur dioxide ($SO_2$) into the atmosphere and oceans, triggering rapid global warming. The warming of the atmosphere and surface ocean waters directly reduced the solubility of oxygen in seawater, leading to widespread marine anoxia. Because warmer water holds less dissolved gas, the marine organisms suffocated. The volcanic activity, rather than any biological changes on land, was the sole trigger of the crisis.

Based on the viewpoints of Student 1 and Student 2, match each scientific factor on the left with the correct description of the students' disagreement on the right.