It is repeatedly claimed that the dumping of nuclear waste poses no threat to people living nearby. If this claim could be made with certainty, there would be no reason for not locating sites in areas of dense population. But the policy of dumping nuclear waste only in the more sparsely populated regions indicates, at the very least, some misgiving about safety on the part of those responsible for policy. Which one of the following, if true, would most seriously weaken the argument? ['Until there is no shred of doubt that nuclear dumps are safe, it makes sense to situate them where they pose the least threat to the public.', 'There are dangers associated with chemical waste, and it, too, is dumped away from areas of dense population.', 'In the event of an accident, it is certain that fewer people would be harmed in a sparsely populated than in a densely populated area.', 'Dumping of nuclear waste poses fewer economic and bureaucratic problems in sparsely populated than in densely populated areas.']