City councilperson: Many city residents oppose the city art commission' s proposed purchase of an unusual stone edifice, on the grounds that art critics are divided over whether the edifice really qualifies as art. But I argue that the purpose of art is to cause experts to debate ideas, including ideas about what constitutes art itself. Since the edifice has caused experts to debate what constitutes art itself, it does qualify as art. Which one of the following, if assumed, enables the conclusion of the city councilperson's argument to be properly inferred? ['If an object causes debate among experts, no expert can be certain whether that object qualifies as art.', 'Any object that fulfills the purpose of art qualifies as art.', 'The purchase of an object that fulfills the purpose of art should not be opposed.', 'Nothing qualifies as art unless it causes debate among experts.']