What determines the difference between a variable and a fixed cost? Select one: O a. Whether the total cost is relevant to a particular decision. O b. Whether the total cost changes when activity levels change. O c. Whether the total cost can be traced to a specific cost object. O d. Whether the total cost is related to manufacturing or nonmanufacturing activities. 1. Product costs refer to: Select one: O a. Direct materials, direct labor, manufacturing overhead and selling and administrative costs O b. Direct materials, direct labor and manufacturing overhead Oc. Direct labor and direct materials only Od. Direct materials only Next page