Which of the following is true about thelong-run average costcurve?

A.

The shape of thelong-run average cost curves is determined by the law of diminishing marginal returns.

B.

Thelong-run average cost curve is the locus of points of the minimum points of thefirm's short-run average total cost curves.

C.

Thelong-run average cost curve is the envelope of thefirm's short-run average cost curves.

D.

Thelong-run average cost curve is the locus of points of the minimum points of thefirm's short-run average variable cost curves.