Consider this scatter plot of the average inflation-adjusted U.S. domestic airfare price from the fourth quarter of every year from 1995 to 2014. Scatter plot of the average inflation-adjusted U.S. domestic airfare price from the fourth quarter of every year from 1995 to 2014 Access image details Source: United States Department of Transportation Which of the following statements are true? (Select all that apply.) The data set represents a time series. The data set is cross sectional. There is a positive relationship between the average inflation-adjusted U.S. domestic airfare price and year. There is a negative relationship between the average inflation-adjusted U.S. domestic airfare price and year.