Passage Summary: An expert says a concert will only fail to sell out if the promotion is bad. Since the concert didn't sell out, the promotion must have been bad.

Conclusion: The recent concert was likely not advertised effectively.

Reasoning: An expert stated that the concert would definitely sell out unless it was poorly promoted, and the concert failed to sell out.

Analysis: This argument follows a valid deductive structure known as Modus Tollens: If P, then Q; Not Q, therefore Not P. The 'unless' phrase creates a conditional requirement where a sell-out is guaranteed by good promotion. To find the match, look for an answer choice that establishes a conditional guarantee and then concludes the condition was missing because the result didn't happen.