Final answer:
The NOT characteristic of a decision support system is that it makes the one best or optimal decision, since DSS are designed to support human decision-making rather than giving definitive answers.
Step-by-step explanation:
The characteristic of a decision support system (DSS) that is NOT usually defined is D) It makes the one best or optimal decision. Decision support systems are designed to aid in solving ad hoc problems, perform what-if analysis, and help managers make decisions using statistical and mathematical models. However, they do not necessarily make the 'one best or optimal decision' because they are intended to support human decision-making, which involves evaluating various alternatives and often relies on managerial judgment rather than providing a single definitive answer. DSS provides a framework to evaluate different scenarios and strategies, but the decision-maker ultimately selects the final course of action.