Comprehensive and Detailed In-Depth Explanation:
Under the variable costing method, only costs that vary directly with production volume are treated as product costs. This includes direct labor costs (the wages of employees directly involved in manufacturing) and manufacturing supplies (materials consumed during production). Insurance on a factory is a fixed overhead cost, and packaging and shipping costs are typically considered period costs or selling expenses, as they are incurred after production. Therefore, options 1 and 3 correctly represent product costs under variable costing.