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When is a traditional (volume-based cost system) appropriate for a service company? O a. A volume-based cost system is appropriate for a service company when certain customers require more attention and a higher level of service than other customers. O b. A volume-based cost system is always appropriate for a service company. O c. A volume-based cost system is never appropriate for a service company. O d. A volume-based cost system is appropriate for a service company when every customer places a similar demand on the company's resources