A state DOT reports that traffic fatalities decreased by 15% after implementing a corridor safety program, but overall VMT also decreased by 12% during the same period. What methodological concern should a safety analyst raise?

1. No concern; the fatality reduction proves the program was effective
2. The observed reduction may be largely attributable to reduced exposure (VMT) rather than the safety treatment, requiring a more rigorous evaluation method
3. The VMT decrease means the data is unreliable
4. The program should be considered a failure because VMT decreased