Answer:
Series A: It is in the nature of variable cost . As we can see that that the cost per unit is (3600 /400 = $ 9 per unit ) and it is applicable at each level of activity.
Series B: Its is in the nature of mixed cost i.e. blend of fixed and variable cost . here Fixed cost is $ 2,500 and Variable cost per unit is ( 3100-2500 /400 units = 1.50 per unit). The same is applicable for each level of activity.
Series C: It is also in the nature of mixed cost (i.e. blend of fixed and variable cost. Here the fixed cost is $ 5400 adn variable cost per unit ( change in cost / change in units ) ( 6600-6000 /800-400 = $ 1.50 per unit)
Series D: It is in the nature of Step wise cost. In Step wise cost, the cost will increase by a fixed amount after it crosses a defined level of activity. Here we can see that the cost is increased by $ 1000 adn the cost structure is as follows:
For Activity level of 0 and 400 units, Cost is $ 1000
For activity level of 800 and 1200 units, Cost is $ 2000 (increase by fixed amount of $ 1,000 for next level )
For activity level of 1600 and 2000 units, cost is $ 3000 (again increase by fixed amount $ 1000 for next level of activity)
Series E: It is in the nature of Fixed cost. As we can see that for any level of activity, the cost remains same i.e. $ 5,000