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.