Missed-item diagnostic record for Transit station music. Argument: After classical music was played in a station, loitering complaints declined. The transit agency concludes that classical music directly discourages loitering. Original stem: "Which choice most weakens the argument?" Student's selected answer summary: the student selected a choice about musical taste. Credited-answer rationale summary: the credited answer notes that extra staff were assigned to the station during the same weeks. Diagnostic complexity note: The record is high-complexity: several answer traps reuse accurate words from the stimulus, and classification requires separating the task from the topic. Which diagnosis correctly labels this missed item by domain, question subtype, difficulty, and dominant error source?