I have to answer on here because you don't have enough choices in your poll. lol! I say beautiful girls CAN be smart! Absolutely for sure. The theory you mention is wrong because looks have nothing to do with smartness. We're given our looks, intelligence, talent, etc when we are created according to God's plan. It has nothing to do with attractiveness.
I think neither is true. A totally nasty girl could also be as stupid as a box of rocks just as well as a beautiful girl could be a rocket scientist. I don't think I'm amazingly attractive but I know I'm not unattractive and I'm also rather smart.. I think that's a poor stereotype and someone should punch him in the face lol