The answer is, it depends.
It depends on whether the dispatcher at the time has created a multi-select of multiple talkgroups, and if so, which talkgroup is the "super-group" of the multi-select.
A multi-select is a patch of 2 or more talkgroups together as one. It's used to allow 1 dispatcher to work multiple talkgroups as a single channel.
Most of the time, talkgroup 21392 is going to be your best bet. Occasionally, you may find that troopers working Union Co are heard on 29072, 46128, 21104.
I would program all 4 of those and listen closely for a week or more until you get comfortable hearing what you want to hear.