In order to operate a competitive, yet profitable business, a real estate broker needs to be concerned with "desk cost." Which of the following most nearly represents the correct way to calculate desk cost:

A: Add the total of all the furniture for each salesperson;
B: Calculate the gross annual profit for the firm, less the expenses, divided by the number of salespersons;
C: Divide the total cost of rent, utilities, and advertising by the number of salespersons;
D: Divide the total operating expenses of the firm, including salaries, rent, insurance, etc., by the number of salespersons.

Answer: D: Divide the total operating expenses of the firm, including salaries, rent, insurance, etc., by the number of salespersons.