Final answer:
Opportunity cost is the value of the best alternative forgone when making a decision, such as choosing a particular investment over others.
Step-by-step explanation:
The term that refers to the best option forgone when a particular investment is selected is known as opportunity cost. Opportunity cost is the value of the next best alternative that one gives up when making a decision. For instance, if you decide to invest in a new business venture, your opportunity cost might be the stock investments you did not make. The opportunity cost varies from person to person, as it is based on each individual's preferences and the alternatives available to them. Understanding opportunity cost is crucial in making informed decisions, particularly with regard to investments and finance.