37. In a temperate forest ecosystem, a mutation spreads through fungal populations that prevents the formation of multicellular hyphae, restricting fungi to unicellular growth forms. Although metabolic pathways for enzyme production remain intact, the organisms cannot form extensive filamentous networks in soil or woody substrates. Which ecosystem-level process would most likely experience the greatest decline as a direct consequence?
(A) Net primary productivity by autotrophs
(B) Atmospheric nitrogen fixation rates
(C) Oxygenic photosynthesis in the canopy
(D) Breakdown of lignin-rich plant biomass
(E) Carbon fixation by soil microbes