Aromatic halides are not reactive enough to give a phosphonium salt. I think you understand the question fine, but you haven't answered why.
One thing, though. 'wittig preparation' is probably colloquially ok, but not a technical term. We're preparing phosphonium salts, or perhaps 'Wittig salts', but we aren't forming phosphorus ylides. It is the ylide that participates in the Wittig reaction.