Read the passage below carefully:
For decades, marine biogeochemical models treated phytoplankton exudation and zooplankton grazing as the exclusive drivers of dissolved organic matter (DOM) recycling in the surface ocean. However, recent oceanographic surveys have highlighted the viral shunt—a process in which viral lysis of marine microorganisms redirects cellular carbon away from higher trophic levels and directly into the microbial loop. While early researchers assumed that viral lysis merely represents a minor loss factor in primary productivity, accumulating metagenomic evidence demonstrates that viral activity actually accelerates the turnover of labile organic nutrients, maintaining high metabolic rates among heterotrophic bacteria. Consequently, viral lysis functions not merely as a pathway of mortality, but as an indispensable regulatory mechanism that sustains nutrient availability in oligotrophic marine ecosystems. Despite these findings, some ecological models continue to underrepresent viral dynamics, relying on simplified grazing rates that risk miscalculating oceanic carbon sequestration.
Which structural function on the right best matches each excerpt cited from the passage on the left?
- "For decades, marine biogeochemical models treated phytoplankton exudation and zooplankton grazing as the exclusive drivers of dissolved organic matter (DOM) recycling in the surface ocean."Historical consensus presented as background context
- "Consequently, viral lysis functions not merely as a pathway of mortality, but as an indispensable regulatory mechanism that sustains nutrient availability in oligotrophic marine ecosystems."Central thesis and primary claim of the passage
- "accumulating metagenomic evidence demonstrates that viral activity actually accelerates the turnover of labile organic nutrients, maintaining high metabolic rates among heterotrophic bacteria."Empirical supporting evidence cited to substantiate the main argument
- "some ecological models continue to underrepresent viral dynamics, relying on simplified grazing rates that risk miscalculating oceanic carbon sequestration."Practical implication illustrating a deficiency in existing frameworks