u/Err79

A question for those more steeped in the history/mechanics of this game than I:

I'm aware you need to leave enough TUs to shoot when you end your turn in order to have the chance to take an overwatch shot during the opposition's turn. Each weapon usually features multiple different shot types with different TU requirements to use. Such as Snapshot, Regular, Aimed and 3-round Burst Fire for the rifle-class weapons. So my question:

How do you know which shot type will be used during overwatch? Or is it always the lowest TU cost shot (usually Snapshot) only?