Kray Incorporated, which produces a single product, has provided the following data for its most recent month of operations;Numberof units producedVariable costs per unit:Direct materialeDirect laborVariable manufacturing overheadVariable selling and administrative expenseFixed costs:$6,000$$ $40$$ $19$$ $8$$ $21$Fixed manufacturing overheadFixed selling and administrative expense$$144,000$$$198,000$There were no beginning or ending inventories. The variable costing unit product cost was:A$)$ $$67$ per unit$8)$ $$61$ per unitC$)$ $$69$ per unitD$)$ $$91$ per unit