Final answer:
The statement 'An unsold service is gone forever' is true because services are perishable and cannot be stored or resold once the time has passed, making demand management vital.
Step-by-step explanation:
The statement "An unsold service is gone forever" can be considered true. Services are described as perishable, which means that they cannot be stored, saved, returned, or resold once the time has passed. If the service is not utilized at the time it is offered, such as a seat on an airplane or an appointment for a haircut, that opportunity to sell the service is lost. This concept is especially important in industries like hospitality, transportation, and entertainment. Being unable to stock or inventory these services like physical goods means that maximizing efficiency and managing demand is crucial.