Using the three variables in the data set loaded by hamcountydata.R, answer the following questions. a. Determine the order of integration of each of the three variables (i.e. determine how many times each variable needs to be differenced to obtain a stationary version). Explain your conclusion and provide evidence to support it. b. Build a dynamic regression model for the unemployment rate (as the dependent variable) that includes an appropriate number of lags of all the variables, etc. c. Test for serial correlation in your best model (provide the evidence and explain your findings). d. What evidence do you find, if any, of relationships between these variables over time (i.e. explain to what extent the other variables help predict the unemployment rate)?