which screen is the right screen

which screen is the right screen for publishing to app store? i would like my app to be compatible with iPhone and ipad and i have done the matrix part of it but don’t know which screen is the right screen since they each have different size.
is the 2:3 for iphone or the 320X480 because they each look different same goes for ipad. Lits say i do chose 2:3 for iphone is that the same for the iphone 4g ?

That’s purely for testing different screen sizes in the editor and has nothing to do with the final build.