Which of the Following Represents a Correct Flow of Electrons $\rarr$

Which of the following represents a correct flow of electrons for nitrogen fixation?

A) ferredoxin $\rarr$ Fe protein $\rarr$ MoFe protein $\rarr$ N₂
B) Fe protein $\rarr$ MoFe protein $\rarr$ ferredoxin $\rarr$ N₂
C) MoFe protein $\rarr$ Fe protein $\rarr$ ferredoxin $\rarr$ N₂
D) ferredoxin $\rarr$ MoFe protein $\rarr$ Fe protein $\rarr$ N₂
E) none of the above