Steuben company produces dog houses. during the current year, steuben company incurred the following costs: rent on manufacturing facility $ 250,000 office manager's salary 150,000 wages of factory machine operators 110,000 depreciation on manufacturing equipment 50,000 insurance and taxes on selling and administrative offices 30,000 direct materials purchased and used 170,000 wages paid to factory machine operators in producing the dog houses should be categorized as a: