An interesting question. Thinking back to GS, sweep increases roll stability, but I'm not sure about directional.
If "directional" means the heading or the direction the nose is pointing then I would have thought that it decreases stability, because sweep tends to be more predesposed to dutch roll tendancies unless some other fix as applied such as really large fins, reduced dihedral, yaw dampers, etc.
If "directional" means track than I would have thought C is the answer.
I suspect "directional" references the heading. My thoughts would be that with all other things considered constant, increased sweep reduces directional stability. In which case, I would have thought B ("Negative") is the answer.