IReadOnlyList<GeographicTransformationListEntry> GetPredefinedGeographicTransformationList()

// a geographic transformation is the definition of how to project from one spatial reference to another
IReadOnlyList<GeographicTransformationListEntry> list = GeometryEngine.Instance.GetPredefinedGeographicTransformationList();

// a GeographicTransformationListEntry consists of Name, Wkid, the From SpatialReference Wkid, the To SpatialReference Wkid
GeographicTransformationListEntry entry = list[0];

int fromWkid = entry.FromSRWkid;
int toWkid = entry.ToSRWkid;
int wkid = entry.Wkid;
string name = entry.Name;