Despite increasing international efforts to protect the natural habitats of endangered species of animals, the rate at which these species are becoming extinct continues to rise. It is clear that these efforts are wasted. Which one of the following, if true, most weakens the argument? ['Many countries do not recognize the increased economic benefit of tourism associated with preserved natural habitats.', 'Species that would have become extinct have been saved due to the establishment of animal refuges.', 'Scientists are better able to preserve the habitats of endangered species now than ever before.', 'Scientists estimate that at least 2000 species become extinct every year.']