Great art style!
I think I like "A" the most. Have you thought about a combining "A" and "C" with the outer lines black and the inner lines colored?
<img src="http://sebastianchamplain.com/temp/sandy.png" border="0" />
I don't mean to nitpick, but the combination of mole and hints of hair from behind her left cheek looks like stubble to me. Maybe consider removing the mole or place it on the other side of her face? Maybe extend the hair longer? If not, I'm sure people like me will figure it out.
I really like your overall design. It's both strong and appealing. Good luck with your game!