A city implemented a new public safety campaign focusing on pedestrian awareness. In the following year, pedestrian accidents decreased. The city council concluded the campaign was effective. Which of the following, if true, most weakens the city council's conclusion?
✓ Correct Answer: Option B
If the number of pedestrians decreased, it provides an alternative explanation for the drop in accidents, independent of the campaign's effectiveness. This directly weakens the conclusion that the campaign caused the decrease.