Last year the Lalolah River was ranked by the Sunvale Water Commission as the most polluted of the fifteen rivers in the Sunvale Water District. Measures taken to clean up the river must be working, though, since this year the Lalolah River is ranked as only the third most polluted river in the district. The reasoning in the argument is flawed because the argument ['equates a decrease relative to the other ranked rivers with an absolute decrease', 'interprets lack of evidence for a claim as support for an opposing claim', 'confuses the state of the individual rivers in the water district with that of the water district as a whole', 'does not disclose the basis for the ranking used']