In 1995, ecologists started to reintroduce the wolf into Yellowstone Park, where the wolf had been eliminated intentionally half a century earlier. Rangers expected a rise in the number of wolf would place limits on the elk population and on the populations of many mid-size mammals. One unexpected consequence was a dramatic rise in the population of foxes, which in turn helped to control many rodent populations. Which of the following, if true, most helps explain the dramatic rise in the fox population? ['Foxes choose very different breeding area than do wolves', 'Elk hunting is more popular, and more widely marketable, than is fox hunting', 'The main predators of the fox were coyotes, on which the wolf preys.', 'In the agricultural counties surrounding Yellowstone, there are significantly lower wolf and fox populations.']