An argument states: 'A city decreased its public transit fares by 20% and saw a 10% increase in ridership. Therefore, lowering fares is an effective strategy to reduce traffic congestion.' What unstated assumption is central to the argument's conclusion about reducing traffic congestion?
✓ Correct Answer: Option B
For lower fares to reduce traffic congestion, the increased ridership must come from individuals who would otherwise drive, not from existing public transit users or those who would have walked/cycled.