The Short-Run Average Total Cost,average Variable Cost,and Marginal Cost Curves

Multiple Choice

The short-run average total cost,average variable cost,and marginal cost curves are all U-shaped because of
i.constant total fixed cost.
ii.increasing and then decreasing marginal returns as more labor is hired.
iii.economies and diseconomies of scale as the plant size increases.

A) only i
B) only ii
C) i and iii
D) ii and iii
E) i, ii, and iii