Determine whether each of the following companies is best suited for a job order cost system, a process costing system, or both.
a. C. Erickson & Sons, Inc. (a construction company with multiple job sites).
b. Apple Computer (a manufacturer of computers for individual and institutional clients).
c. PlayWorld Systems, Inc. (a provider of custom-designed playground equipment for city parks and schools districts).
d. Strong Industries (a manufacturer of injection-molded plastic doghouses).
e. Nature Made Nutritional Products (a maker of vitamins and nutritional supplements).