Environmentalist: The complex ecosystem of the North American prairie has largely been destroyed to produce cattle feed. But the prairie ecosystem once supported 30 to 70 million bison, whereas North American agriculture now supports about 50 million cattle. Since bison yield as much meat as cattle, and the natural prairie required neither pesticides, machinery, nor government subsidies, returning as much land as possible to an uncultivated state could restore biodiversity without a major decrease in meat production. Which one of the following most accurately expresses the environmentalist's main conclusion? ['If earlier North American agricultural techniques were reintroduced, meat production would decrease only slightly.', 'Protecting the habitat of wild animals so that we can utilize these animals as a food source is more cost effective than raising domesticated animals.', 'The devastation of the North American prairie ecosystem could be largely reversed without significantly decreasing meat production.', 'Preservation of the remaining North American bison would be a sensible policy.']