In linear programming models of real problems, the occurrence of an unbounded solution means that the problem formulation is improper. Thus the correct option is D.
A mathematical method called linear programming identifies how to make the optimum use of the resources available. The procedure is used by managers to make judgments about how to use their limited resources as effectively as possible.
When an unbounded solution appears in linear programming models of actual situations, it indicates that the issue formulation is flawed. When an objective value can be increased or lowered without restriction, a model is said to be unbounded.
Therefore, option D is appropriate.
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