-As Output Increases, the Distance Between the Average Variable Cost

-As output increases, the distance between the average variable cost curve and average total cost curve narrows because:

A) economies of scale give way to diseconomies of scale.
B) marginal cost is increasing as the level of output increases.
C) the difference between the two curves represents average fixed cost, which is decreasing.
D) problems created by the Law of Diminishing Returns worsen.