Mccaskell Corporation's relevant range of activity is 7,000 units to 11,000 units. When it produces and sells 9,000 units, its average costs per unit are as follows: Average Cost per Unit Direct materials $ 6.30Direct labor $ 3.65Variable manufacturing overhead $1.75Fixed manufacturing overhead $ 9.90Fixed selling expense $ 2.25Fixed administrative expense $ 1.80 Sales commissions $ 1.00Variable administrative expense $ 0.501f 18.000 units are produced, the total amount of direct manufacturing cost incurred is closest to: .a. $79,600 b. $93.600 c. $87,600 d. $172,800