The following are costs associated with manufacturing firms, merchandising firms, or service firms: a. Miscellaneous materials used in production b. Salesperson's commission in a real estate firm c. Administrators' salaries for a furniture wholesaler d. Administrators' salaries for a furniture manufacturer e. Freight costs associated with acquiring inventories for a grocery store f. Office manager's salary in a doctor's office g. Utilities for the corporate offices of a toy manufacturer h. Line supervisor's salary for a clothing manufacturing firm i. Training seminar for sales staff of a service firm j. Fuel used in a trucking firm k. Paper used at a printing business l. Oil for machinery at a plastics manufacturing firm m. Food used at a restaurant n. Windshields used for a car manufacturer Classify the costs as (1) product or period; (2) variable or fixed; and (3) for those that are product costs, as direct materials, direct labor, or manufacturing overhead. Write "not applicable (N/A)" if a category doesn't apply