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.

a 1-Product 2-Variable 3-Manufacturing Overhead
b 1-Period 2-Variable 3- N/A
c 1-Period 2-Fixed 3- N/A
d 1-Period 2-Fixed 3-Manufacturing Overhead
e 1-Product 2-Variable 3-Direct Material
f 1-Period 2-Fixed 3- N/A
g 1-Period 2-Variable 3- N/A
h 1-Period 2-Fixed 3-Manufacturing Overhead
I 1-Product 2-Variable 3-Direct Labor
j 1-Period 2-Variable 3- N/A
k 1-Product 2-Variable 3-Direct Material
l 1-Product 2-Variable 3-Manufacturing Overhead
m 1-Period 2-Variable 3- N/A
n 1-Product 2-Variable 3-Direct Material

More instructions:
All costs will be either fixed or variable.
Not all costs are period or product so some will reflect NA.

Not all costs will be defined as material, labor, and overhead so some will have NA.

Can someone tell me if I am headed in the right direction, and where would NA come into play if not all costs are period or product?

Thanks for your help!