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 d_L 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.