Under What Conditions Is Swidden Cultivation Sustainable

Under what conditions is swidden cultivation sustainable?

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