Following are five series of costs A through E measured at various volume levels. Identify each series as either fixed, variable, mixed, step-wise, or curvilinear. Volume (Units) 0 400 800 1,200 1,600 2,000 2,400 Series A $ 0 7,700 8, 470 9,240 10,523 12,320 17,325 Series B $4,400 4,400 5,400 5,400 6,400 6,400 7,400 Series c $ 8,400 8,400 8, 400 8,400 8,400 8,400 8,400 Series D $ 0 4,960 9,920 14,880 19,840 24,800 29,760 Series E $4,200 4,800 5,400 6,000 6,600 7,200 7,800 Series A Series B Series C Series D Series E Mixed cost Curvilinear cost Step-wise cost Fixed cost Variable cost