The national speed limit in the United States was reduced to 55 mph in 1974 . Proponents and critics ...

The national speed limit in the United States was reduced to 55 mph in 1974 . Proponents and critics of this legislation have looked at the number of traffic fatalities on each of the major U.S. highways (e.g., I-90, I-65, I-75) for the years preceding and following this legislation. The examination of traffic fatalities on each of the various highways illustrates the use of
 
  a. pretest-posttest one-group design.
  b. the time-series design.
  c. the multiple time-series design.
  d. the nonequivalent control group design.
  e. the one-shot case study.