Suppose, at a given point in time, Quinn's Quarry operates in a perfectly competitive market and is producing its profit-maximizing level of output. Suppose further that at this level of production its average total cost of producing granite is $38, average variable cost is $29, and marginal revenue is $42. At this moment, Quinn is earning _____ economic profits. Over time, everything else held constant, the amount of granite produced by Quinn will _____.

Select one:

A.positive; increase

B.zero; remain unchanged

C.negative; increase

D.positive; decrease

E.negative; decrease