The answer is C.
(A) Capeville, a neighboring city, has only one parking garage, though it was not filled every day of the month.
Incorrect. This option does not weaken the argument because it is irrelevant to the situation in Williamstown. The parking patterns in a different city do not provide any evidence about the likelihood of the Williamstown parking garage being full in September.
(B) In July, the Williamstown parking garage was full every day of the month.
Incorrect. This statement reinforces the conclusion rather than weakens it. While it shows a trend of popularity, it does not provide any reason to believe that the situation will change in September. Past occupancy does not inherently challenge the prediction for the future.
(C) Williamstown is a popular beach town and tourists across the nation flock to its beaches from June to August, but the city becomes virtually empty come September.Correct. This option effectively undermines the conclusion by suggesting that the parking garage's full capacity in August is due to seasonal tourist influx. If September sees a significant decrease in visitors, the likelihood of the garage being full also decreases.(D) This coming September, the Williamstown City Council is inaugurating the first annual September rock festival, which will feature performances throughout the month by popular musicians.
Incorrect. This option does not weaken the argument; instead, it potentially strengthens it. The festival could attract a considerable number of visitors to the area, suggesting that the parking garage might remain full. While it introduces an event that could maintain parking demand, it does not address the assumption that the overall trend of visitor numbers will drop in September.
(E) The Grand Hotel, a popular hotel in Williamstown, expects to have a full garage the entire month of September.
Incorrect. This option also does not weaken the argument; rather, it supports the possibility of continued demand for parking. The expectation of a full garage at the hotel indicates that there may still be enough visitors in September to keep the main city parking garage busy.