Under What Conditions Is Swidden Cultivation Sustainable

Under what conditions is swidden cultivation sustainable?

A) when long-term weather patterns provide adequate moisture and warmth
B) when the government intervenes to control land use
C) when private entities purchase land for development
D) when population densities remain low, and where upland people control enough land
E) when there is a large number of people to do the hard, manual labor associated with swidden