Identify Cost Graphs

The following cost graphs illustrate various types of cost behavior:

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

a. Total direct materials cost

b. Electricity costs of $1,000 per month plus $0.10 per kilowatt-hour

c. Per-unit cost of straight-line depreciation on factory equipment

d. Salary of quality control supervisor, $20,000 per month

e. Per-unit direct labor cost