It's whichever terminal is at AC common (ground).
AC ground is a node that is connected to ground through a capacitor, thus it can have a DC value different from ground but will be at AC ground for any frequencies of interest. DC ground is the same as ground (i.e. it's ground for DC or AC).how do I identify AC Ground vs DC Ground?
If you have a node connected to "ground" via an inductor, that "ground" will be DC ground but not AC ground.AC ground is a node that is connected to ground through a capacitor, thus it can have a DC value different from ground but will be at AC ground for any frequencies of interest. DC ground is the same as ground (i.e. it's ground for DC or AC).