3) 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. 5) Marginalism is A) the best alternative that we forgo when making a decision. B) the study of how societies choose to use scarce resources. C) a market situation in which profit opportunities are eliminated almost instantaneously. D) the process of analyzing the additional costs or benefits arising from a decision