Under What Conditions Is Swidden Agriculture Sustainable

Under what conditions is swidden agriculture sustainable?

A) when the government intervenes to control land use
B) when private entities purchase land for development, minimizing the acreage of land used for swidden agriculture
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