Five years ago, the town of Bayside, in the Katonic River Valley, had catastrophic flooding one spring, and consequently, most insurers now refuse to write flood insurance for houses in Bayside. The town of Dryadia, in the Phemptic River Valley, is much like Bayside in its proximity to a similar river at an almost identical point in the river valley. We can conclude that the only reason the same insurers do not write flood insurance for houses in Dryadia either is its similarity to Bayside in terms of where it is situated in the river valley. Which of the following, if true, would most seriously undermine the argument? ['In many other towns in the Katonic River Valley, it is hard for home-owners to buy flood insurance.', 'The town of Dryadia has some flooding most springs.', 'Flooding from spring surges in rivers is only one of the ways in which a home can become flooded.', 'A small number of independent insurers will write flood insurance for at least some houses in each of the two towns.']