A city official claims that a new express bus service will significantly reduce downtown traffic congestion because it offers a faster alternative for commuters. Which of the following, if true, would most weaken the official's claim?

✓ Correct Answer: Option C

The official's claim assumes commuter traffic is the primary cause of congestion. If a substantial portion is non-commuter, a service targeting commuters will have a limited impact, thus weakening the claim of significant reduction.