Please identify each series as either fixed, mixed, variable, or step wise.

Following are four series of costs measured at various volume levels. Identify each series as either fixed, variable, mixed, or step-wise Hint. It can help to graph each cost series. Volume(Units)04008001,2001,6002,0002,400SeriesA$5,2405,2405,2405,2405,245,245,240SeriesB$1,241,2402,4802,4803,723,7204,960SeriesC$03,8407,68011,52015,36019,20023,040SeriesD$2,7403,3403,9404,5405,1405,7406,340 \begin{tabular}{|l|l|l|l|} \hline Series A & & \\ \hline Series B \\ \hline Series C & & \\ \hline Series D \\ \hline \end{tabular}