18) The principal difference between variable costing and absorption costing centers on: A) whether fixed manu facturing costs and fixed selling and administrative costs should be included in product costs. B) whether variable manufacturing costs should be included in product costs. C) whether selling and administrative costs should be included in product costs. D) whether fixed manufacturing costs should be included in product costs. 19) Under variable costing, fixed manufacturing overhead cost is not treated as a product cost. A) True B) False 0) Under absorption costing, product costs include: Fixed manufacturing overhead A) B) C) D) Variable manufacturing overhead Yes No Yes No Yes No No Yes A) Option A B) Option B C) Option C D) Option D