After a Linear Forecasting Model Is Found for a Time

Multiple Choice

After a linear forecasting model is found for a time series, if the Durbin-Watson statistic is less than dL this means that:

A) no positive autocorrelation exists, the linear model is adequate.
B) positive autocorrelation exists, a nonlinear model should be tried.
C) no positive autocorrelation exists, a nonlinear model should be tried.
D) positive autocorrelation exists, the linear model is adequate.