That which we forgo, or give up, when we make a choice or decision is called

A) out-of-pocket cost.
B) marginal cost.
C) real cost.
D) opportunity cost.

Opportunity Cost

The loss of potential gain from other alternatives when one alternative is chosen, a fundamental concept in economics.

Real Cost

The total cost of manufacturing or providing a service, including all direct and indirect costs.

Marginal Cost

The cost of producing an additional unit of a product, highlighting the concept of increment in total cost with an increase in production.