A research team is investigating a novel species of bioluminescent fungi, *Mycena luxnova*, found in a remote cave system. They discover that the fungal bioluminescence relies on a unique luciferin-luciferase system. Unlike typical luciferases, *M. luxnova* luciferase (LuxL) exhibits a significantly reduced catalytic efficiency when utilizing free oxygen ($O_2$) as the terminal electron acceptor. However, the fungi thrive in an environment with extremely low oxygen concentrations (less than 1% atmospheric levels) and maintain high bioluminescence output. Further investigation reveals that LuxL possesses a high affinity binding site for nitrite ($NO_2^−$), and that nitrite reduction by LuxL is coupled to luciferin oxidation, generating light. The team observes that increasing nitrite concentration *in vitro* enhances bioluminescence even further, while increasing oxygen concentration inhibits it. Considering these findings, which of the following BEST explains how *M. luxnova* has adapted its bioluminescence pathway to function optimally in a low-oxygen environment?