Economists study market structures that fall between the two extremes of perfect competition and monopoly for all of the following reasons except​: A. Realistic models of market structure lie somewhere between perfect competition and monopoly. B. Studying the interaction between firms allows us to learn about the nature of competition and how prices are set. C. Counting the number of firms tells us whether the market is competitive. D. Additional models are necessary to help answer questions about how many firms are necessary to make a market competitive.

Kirnon clinic uses client-visits as its measure of activity. during july, the clinic budgeted for 3,250 client-visits, but its actual level of activity was 3,160 client-visits. the clinic has provided the following data concerning the formulas to be used in its budgeting: fixed element per month variable element per client-visitrevenue - $ 39.10personnel expenses $ 35,100 $ 10.30medical supplies 1,100 7.10occupancy expenses 8,100 1.10administrative expenses 5,100 0.20total expenses $ 49,400 $ 18.70the activity variance for net operating income in july would be closest to: