So what hit the south tower, anyway?

Here are all the possibilities I can think of for the south tower hit:

1) nothing flying, purely pre-planted charges
2) cluster of visible unmanned Aerial Vehicles (UAVs)(this could include a wide variety of flying objects including entomopters)
3) cluster of cloaked (invisible) UAVs
4) cloaked (invisible) missile
5) visible large missile (one or two)
6) hologram-projecting missile (showing a Boeing jet)
7) UA175
8) some other large Boeing, possibly modified

Numbers 2-6 in theory could be combined with pre-planted charges.

Because pictures of the south tower "entry" hole show columns knocked inward, I tend to favor possibilities where some flying object hits the tower.

Because videos show conflicting plane paths (and because of the strong evidence in general that the videos had artificial planes inserted in them), this suggests to me that the flying object was invisible, or only weakly visible (a blur, perhaps only seen from certain angles). That is, the videos were not simply inserting an image over some foreign flying object that was not a Boeing 767-- the videos were making up the flight path of the 767, and this varied from video to video.

All this basically leaves possibilities 3 and 4-- cluster of cloaked (invisible) UAVs
or a cloaked (invisible) missile. The problem with missiles is how did they create the wing-scars? This leaves the cloaked UAV idea as the strongest possibility, where the UAVs were able to chew up sections of the outer columns and knock columns inward, and assist in the propulsion of the explosion out the northeast corner of the south tower.

The other possibility is that somehow pre-planted charges were set-up that could specifically knock columns inwards, though this would presume extraordinary access to the building right before 9/11. Of course, there was a major power down of the top half of the south WTC tower the weekend before 9/11, with lots of workmen coming and going.