Classify each of the following independent costs as product or period costs and whether they are variable or fixed cost by placing an "X" in the relevant box. Assume that a cost object is a unit of product produced. COST Product Period Variable Fixed Sheet aluminum used in making airplanes. Annual salary of assembly line supervisor. Insurance on the automotive factory. Depreciation on the corporate office building using the straight-line method. Advertising costs incurred for a radio advertisement. Wages of finished goods quality inspectors. They inspect 1 out of every 100 products