Which statement best explains this excerpt from act 5 scene 1 of twelfth night?

Sebastian explains that the case of mistaken identity has worked in Olivia's favor because she has married Sebastian, not Viola.

Nature's bias is actually that a woman cannot marry another woman, but that is fixed with this outcome of events. However, the fact that she married a maiden is not completely wrong, because Sebastian is himself a virgin, therefore "both a maid and a man".