A partial listing of costs incurred during December at Rooks Corporation appears below: Factory supplies $ 21,000 Administrative wages and salaries $ 118,000 Direct materials $ 166,000 Sales staff salaries $ 81,000 Factory depreciation $ 62,000 Corporate headquarters building rent $ 47,000 Indirect labor $ 45,000 Marketing $ 116,000 Direct labor $ 96,000 The total of the product costs listed above for December is:

a. $375,000 b. $128,000 c. $752,000 d.$390,000