It depends on how the beer tastes
My initial reaction is that 28c is more appropriate because 29b requires that you list a base style of beer. If you didn't start out with a "base style" and then add fruit and spice to it, then I think 29b is out.
That said, it all depends on taste - so if I drink your beer and say "wow that's a great example of a berliner weisse with a nice addition of raspberries and blackberries and subtle vanilla undertone" (whether that was your intention or not) then 29b would work just fine.
If your beer is funky, not recognizable as a base style, and all of the elements of vanilla, raspberry and blackberry are detectable then I would go with 28c
It's also important to remember that you should only declare ingredients you can actually detect in the beer. If you declare it, then the judges will be looking for it, and if they don't taste it they should deduct points for that. Judges will evaluate your beer based on what is in front of them and don't get the know what you intended