In the context of Pareto efficiency, which scenario best illustrates a market failure where opportunity costs are not fully realized?

Pareto efficiency occurs when resources are allocated in a way that no one can be made better off without making someone else worse off. A market failure happens when this ideal situation is not achieved, often because opportunity costs are ignored. For example, imagine a farmer who decides to grow corn instead of potatoes because corn sells for a higher price. However, if the farmer does not consider that the potatoes would have provided more nutrition for the community, then the opportunity cost of not growing potatoes is significant. This situation shows a market failure because the community's overall well-being could be improved if the farmer had made a different choice, highlighting that not all costs and benefits are being fully realized in the decision-making process.