Walsh Corporation has provided the following information: Cost per Unit Cost per Period Direct materials Direct labor Variable manufacturing overhead $ 6.35 $ 3.75 $ 1.50 Fixed manufacturing overhead Sales commissions Variable administrative expense Fixed selling and administrative expense $ 15,000 $ 0.50 $ 0.55 $ 4,500 If 4,000 units are sold, the variable cost per unit sold is closest to: Select one: O a. $12.65 O b. $11.60 O c. $14.60 O d. $16.55