A Time Series with Forecast Values and Error Terms Is

A time series with forecast values and error terms is presented in the following table.The mean error (ME) for this forecast is ___________. $\begin{array}{|r|r|r|r|}\hline \text { Monthh } & \text { Actual } & \text { Forecast} & \text { Error } \\\hline \text { July } & 5 & & \\\hline \text { Aug } & 11 & 5 & 6.00 \\\hline \text { Sept } & 13 & 6.8 & 6.20 \\\hline \text { Oct } & 6 & 8.66 & -2.66 \\\hline \text { Nov } & 5 & 7.862 & -2.86 \\\hline\end{array}$

A) 1.67
B) 1.34
C) 6.68
D) 3.67
E) 2.87