...
They showed both in the Horizon episode and suggested that both / all are possible.
Of course, these aren't theories as suggested in the programme but hypotheses. There's no actual evidence, apart from complex maths, to back them up.
Complex maths is not evidence, and anyway they didn't bother with showing any. It would have been so very very complex... though I expect we can rely on the narrator having checked it all out personally?
For all intents and purposes those scientists may have been using magic crystal balls kept up their bottoms.
The only point properly explained was the double slit experiment, already done to death over the years and not particularly relevant to the specific topic.
The search for cold spots in th CMB failed to find any any, but they didn't bother explaining this, despite at least 45 minutes of a one hour programme slow panning over beaches, rocks, scientists fiddling with lego and plastic blow up balls instead of explaining any ideas.