Economies of Scale in the Production of a Good Imply

Economies of scale in the production of a good imply that _____

A) the long-run average cost of production rises as the scale of operation expands.
B) the marginal cost of production falls below zero as the scale of operation contracts.
C) the long-run average cost of production falls as the scale of operation expands.
D) the long-run average cost of production remains the same as the scale of operation increases.
E) marginal output decreases as the amount of a factor of production is incrementally increased.