4. S'Round Sound, Inc. reported the following results from the sale of 24,000 units of IT-54: Sales $528,000 Variable manufacturing costs 288,000 Fixed manufacth costs 120,000 Variable selling costs 52,800 Fixed administrative costs 35,200 Rhythm Company has offered to purchase 3,000 lT-54s at $16 each. Sound has available capacity, and the president is in favor of accepting the order. She feels it would be protable because no variable selling costs will be incurred. The plant manager is opposed because the "full cost" of production is $17. Which of the following correctly notes the change in income if the special order is accepted? A. $3,000 decrease. B. $3,000 increase. C. $12,000 decrease. D. $12,000 increase