For each of the following costs, identify the cost graph that best describes its cost behavior as the number of units produced and sold increases:

(a)	Sales commissions of $5,000 plus $.05 for each item sold.
(b)	Rent on warehouse of $10,000 per month.
(c)	Insurance costs of $2,500 per month.
(d)	Per-unit cost of direct labor.
(e)	Total salaries of quality control supervisors. One supervisor must be added for each additional work shift.
(f)	Total employer pension costs of $.30 per direct labor hour.
(g)	Per-unit straight-line depreciation costs.
(h)	Per-unit cost of direct materials.
(i)	Total direct materials cost.
(j)	Electricity costs of $5,000 per month plus $.0004 per kilowatt-hour.
(k)	Per-unit cost of plant superintendent's salary.
(l)	Per-unit cost of direct labor.
(m)	Repairs and maintenance costs of $3,000 for each 2,000 hours of factory machine usage.
(n)	Total direct labor cost.
(o)	Straight-line depreciation on factory equipment.