Analyses of traffic accidents in West Harrison and Santiago

Analyses of traffic accidents in West Harrison and Santiago have shown there to be no relationship between traffic accidents and the presence of digital billboards. Similar studies by state police and transportation departments have found consistent results.

Which of the following can be most reasonably concluded on the basis of the information above?

A. There is substantial variation in the volume of traffic accidents between West Harrison and Santiago.
B. West Harrison and Santiago have seen an increase in the volume of traffic accidents in areas where digital billboards have been installed.
C. State police and transportation departments have reviewed the same data as was used in the studies in West Harrison and Santiago.
D. The causal link between traffic accident volume and digital billboards might not yet be conclusive.
E. Additional studies should be conducted to further investigate the causal link between traffic accident volume and digital billboards.

Studies from both parties deny each other's results, So we do not have anything to conclude. I can be wrong. But C is not the right answer. There is no way you can infer from the given statements that both parties use same data, even if they are conducting study on a same topic.
Hope it helps.