In an attempt to reduce the use of gasoline, a city imposed a $2.50 per gallon tax on gasoline in 2005. A researcher working for the city, located data on annual gallons used for the 5 years leading up to the gas tax (to provide a baseline) and located data for the 5 years after the start of the gasoline tax (to show the consumption pattern after the tax). Which of the following best describes this study design?
a. A-B-A-B designb. Changing-criterion design c. Interrupted time-series designd. Regression-discontinuity design