(b) Panel 1C and 1D show the Augmented Dickey-Fuller (ADF) test results for the log(exrate) (i.e., LEXRATE) and the log(CP) (i.e., LCP). Why is the ADF test preferred to the DF test? [2] (c) Write down the unit root test regression specification. [2] Panel 1C (LEXRATE) Panel 1D (LCP) Exogenous: Constant, Linear Trend Exogenous: Constant, Linear Trend Lag Length: 0 (Automatic - based on SIC, maxlag=13) Lag Length: 1 (Automatic - based on SIC, maxlag=13) t-Statistic Prob.* t-Statistic Prob.* Augmented Dickey-Fuller test Augmented Dickey-Fuller test statistic -2.422430 0.3664 statistic -1.613724 0.7827 Test critical Test critical values: 1% level -4.025924 values: 1% level -4.026429 5% level -3.442712 5% level -3.442955 10% 10% level -3.146022 level -3.146165