Parker Beverages sells a variety of protein shakes and fruit juices  to small health food stores. Parker purchases the shakes and juices from leading manufacturers. Identify  each of the following costs incurred by Parker Beverages in terms of its cost behavior—variable, fixed,  mixed, or step.

a. Human resource director salary

b. 8-ounce protein shake

c. Monthly delivery truck lease payment of $350

d. Straight line depreciation on office equipment

e. Shipping (billed in 100-case increments)

f. Sales commission (4% of sales revenue)

g. Copy machine rental (monthly fee of $35 plus $0.01 per copy)