Which box will not accelerate? (pictures, really easy)

And please explain if you can I'm having a .. moment. lol

First two

http://i602.photobucket.com/albums/tt108/slytherin123/F2D33D44-EB35-4652-8B07-868B9B2A0AEF-282-000000028A475F60.jpg

Second two

http://i602.photobucket.com/albums/tt108/slytherin123/30D4625C-B9A1-427E-9DA5-70D41AB7DF5F-282-0000000257255A6B.jpg

Thanks so much you have no idea how much it means.

B will not accelerate because if you look at the forces acting upon it, they are all equal meaning they will cancel each other out. The others will accelerate in the direction with the most force. Hope that helps.

F = ma
But, that force is a NET force i.e. I push a box with 5N forward and there is friction of 5N in the opposite direction, there is no acceleration.

So,
A has a net force of 10N east
B has a net force of 0
C has a net force of 42.4N north east
D has a net force of 15N east

I'm sure you can tell me which will accelerate!