Like most things, probably the combination of all of them. It might be convenien...

		freeflight on Aug 16, 2018 \| parent \| context \| favorite \| on: Bleak New Estimates in Drug Epidemic: A Record 72,... Like most things, probably the combination of all of them. It might be convenient to ask for that "one prime mover", but the reality is usually way too complex for that.