The expansion of large-scale farming in Africa and Asia has destroyed much of the natural vegetation on which elephants have historically depended, forcing them to turn to cultivated land to satisfy their enormous appetites. As a result, farmers have lost millions of dollars worth of crops annually. Yet even if elephant sanctuaries were created on a widespread basis to guarantee elephants sufficient natural vegetation, the raiding would likely persist, since Which of the following most logically completes the argument below? ['when elephants forage for food, they typically travel in herds.', 'Elephants tend to prefer cultivated crops to wild vegetation as a food source.', 'Some of the land where crops have suffered extensive damage from elephants has been allowed to return to its natural state.', 'Elephant sanctuaries are usually created in areas that are rich in the natural vegetation on which elephants have historically depended.']