What is the term for the additional benefit associated with one more unit of an activity?

The term for the additional benefit associated with one more unit of an activity is indeed reflected accurately in the chosen answer. This concept is known as "marginal benefit," which refers to the extra gain that comes from increasing the level of an activity by one more unit. When individuals or businesses evaluate the outcomes of their decisions, they consider marginal benefits to determine if the additional unit of consumption, production, or investment is justified based on the benefits it provides.

In economic theory, understanding marginal benefit is crucial because it helps in decision-making processes. For instance, if the marginal benefit of consuming one more unit of a good exceeds its marginal cost, it would be rational to continue that activity; if not, resources may be better allocated elsewhere. This reasoning directly informs how choices are made in the context of limited resources and competing opportunities.

The other options do not precisely define the concept: opportunity cost relates to what is foregone when a choice is made, total benefit encompasses the entirety of benefits from all units, and opportunity benefit is not a standard term used in economic terminology. Hence, the clear definition captured in the correct answer aligns with established economic principles.