People on Yahoo answers barely play chess...
I don't like the 4 knights, I think white should play Bc4 or Bb5 and not Nc3.
If it does come on the board, then quite simply copy white. Bb5 then Bb4. You may need to take on c3, at least if Nf6 gets pinned by Bg5.
After Bc4 I still consider Nxe4 the main line. Of course you could go Bc5 instead and enter the very quiet Italian game.
Either way it's very calm and doesn't promise white much, if both players are equal of course.
A few comments.
4.Bc4 is a blunder and Black is simply better after 4...Nxe4.
No, it isn't. Actually, white is slightly for preference in the much quoted sequence 4.Bc4 Nxe4 5.Nxe4 d5 6.Bd3 de4 7.Bxe4 Bd6. White should concentrate on pressure against e5 by 8.0-0 0-0 9.Re1! Re8 10.d3 Bg4 11.h3 Bh5 12.c3, where common sense says that white has a slight advantage.
But Black may deviate with 7...Ne7!? which opens up a lot of very tricky tactical variations.
Check your facts better next time, please.
It's nice when we can make our opponents play inferior moves in analysis, isn't it? You say the same about Abby Marshall, but isn't 10...Bg4 a bit too generous? I understand Karjakin played this move in a blitz game, but there are better moves to be had in my opinion, namely 10...h6 as played by two other titled players and 10...Nd4!? which opens a whole new can of worms. :)