The Table Below Includes the Actual Demands and Forecasted Demand

Short Answer

The table below includes the actual demands and forecasted demand for each period.Which of the following is the correct Bias value for this data?
$$\begin{array} { l l l l l l } \text { Period } & 1 & 2 & 3 & 4 & 5 \\\hline \text { Actual Demands } & 100 & 120 & 115 & 90 & 79 \\\text { Forecast Demands } & 90 & 110 & 130 & 135 & 90\end{array}$$