Final answer:
A discussion about multiple optimal solutions in linear programming, relating to how the budget constraint and PPF illustrate tradeoffs and opportunity cost, though specific combinations producing multiple solutions cannot be determined without more details.
Step-by-step explanation:
The original question appears to relate to optimization in linear programming, although the constraints and objective function are not explicitly provided. However, we can still discuss the general idea that having multiple optimal solutions occurs often in linear programming when the objective function is parallel to a constraint line or when multiple constraints intersect at more than one point on the feasible region, creating a scenario where there are several points that could represent the optimal solution. In the context provided, both the budget constraint and the Production Possibilities Frontier (PPF) are brought up, which are graphically similar in showing the tradeoff between two goods and illustrating opportunity cost with their slopes. However, without specifying how the constraints interact with the objective function, it is not possible to determine which combination would produce multiple optimal solutions without additional information.