One of the three, or perhaps a combination.

But it is more diffficult to diagnose, just sitting in a shop on a rack, as the sway bar has to be in a load-transition posture to release pressure on the links, which then rattle. One mechanic can simply drive it and tell, whereas another might tinker with it on the rack and find nothing.

Railroad tracks are ideal for the test, particularly if you can safely side-load a bit going over them (quick lane change for example while the front tires cross them). The way to distinguish is that worn bushings are more likely to be a deeper sound, perhaps a sort of clunking, that can often be felt through the front floorboard; end links are a little lighter in tone and frequency, sometimes described as a rattle. However, just changing the bushings will sometimes then isolate the end links and they start making noise. Same thing with changing the shocks; that stiffened things up and displayed the "weak link".

That's why I suggest changing them together, not to mention that when you change them at the same time it takes pressure off of each, making the whole job easier. It's only 8 fasteners total IIRC.

None of these parts affects alignment, so this is a great way to get a little dirty, gain some satisfaction in a DIY job, and save a good chunk of change. Parts at retail/plus, shop charges and labor, you could drop $350 at the stealer, not to mention the time wasted going there. Of course you won't get their "free" coffee or "complimentary" car wash.