In modern F1, race neutralization via Safety Car is done in two variations, the traditional SC Period, where the Safety Car actually goes out on track and collects the entire field to form a slow-running queue; and the new Virtual Safety Car where the drivers are simply required to run sector times that are over a specified Delta, effectively slowing them down as well.
I understand that the VSC is meant to neutralize the race, slowing down the pace without bunching up the field, but still maintaining the gaps between the cars on track. Something similar to how Full Course Yellow works in WEC, only with the delta time replacing the speed limit.
In case of on-track incidents that exceeds Yellow Flag conditions, how does the FIA decide which Safety Car procedure to use?