Answer:
The variable cost per unit sold is closest to $11.90.
Explanation:
Only variable manufacturing costs are included in product costing under the variable costing method.
Both the fixed manufacturing costs and non-manufacturing costs are treated as period costs, expensed in the profit and loss.
Calculation of Variable Unit Cost
Direct materials                  $ 6.60
Direct labor                     $ 3.65
Variable manufacturing overhead   $ 1.65
Total Variable Unit Cost           $11.90
Conclusion :
The variable cost per unit sold is closest to $11.90.