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) Salary of the night-time security guard of $3,200 per month. (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