[Zewski]

Hey,
I just was wondering what the mechanism of the oxidation of phosphanes with oxygen would be. My professor told me it would be mechanism a), but I found that unlikely due to a nucleophilic attack of a nucleophil on a negativ charged elecrophile...
So tried to think of other mechanisms and came up with mechanism b) and c).
What do you think?
Maybe you have other suggestions aswell?