Given the Following Information

Given the following information:
Compensation - $90,000 Direct Communications - $5,000
Automobile - $7,000 Meals & entertainment - $6,000
Overhead - $12,000 Promotional materials - $10,000
Calls per day - 5 Profit margin - 10%
Net selling days - 200
-Calculating cost-per-call is an important step in addressing the minimum customer size issue. Cost per call is a function of:

A) the number of calls made per day.
B) a salesperson's direct selling expenses.
C) gross margin.
D) both a and
E) all of the above.