The Fifth NEWT and James and Lily as Aurors (also posted on HPfGU)

[Phyllis]

McGonagall tells Harry that a minimum of five NEWTs are required to 
become an Auror, but then she only tells him about four:  Defense 
Against the Dark Arts, Charms, Potions and Transfiguration.  Any idea 
what the fifth one is?  Presumably it's a subject Harry's currently 
taking, or else McGonagall would have told him he's out of the 
running, so presumably this rules out subjects like Ancient Runes and 
Arithmancy.  Which leaves History of Magic, Herbology, Divination or 
Astronomy as potential candidates (any I forgot?).

Also, I thought it was interesting that McGonagall put such a heavy 
emphasis on both Transfiguration and Charms during the career advice 
session, since Ollivander tells Harry in PS/SS that James' wand 
was "excellent for transfiguration" and Lily's was a "nice wand for 
charm work."  This information, coupled with the new knowledge that 
both Lily and James were in the Order during the first war and defied 
Voldemort three times, leads me to change my mind about Lily and 
James being Aurors.  I didn't used to think they were, given that 
they don't appear to fight against Voldemort when he attacked them at 
Godric's Hollow, but I now think they were.

~Phyllis