Elegant Settings Manufactures Stainless Steel Cutlery

Elegant Settings manufactures stainless steel cutlery. Table 11-9 shows the company's cost data.
-Refer to Table 11-9. Elegant Settings experiences

A) economies of scale up to an output level of 400.
B) diminishing returns up to an output level of 400.
C) increasing returns beyond an output level of 400.
D) economies of scale at an output of 300 or less and diseconomies of scale at an output level above 400.