I agree with Bubster that picture C is Mel B.
And I think pic B could be Kylie Minogue.
But as for A, I don't know how anyone is supposed to guess correctly. It could be any brunette! Do wish Best would start giving clues for this comp (or go back to the wordsearch!).
OK just to confuse matters (and myself) today I think B looks more like Nicole Kidman than Kylie Minogue. Another comping website I've seen has had suggestions of Tara Palmer Tompkinson and Fergie from the Black Eyed Peas for B. There was also a suggestion of Demi Moore for pic A.