Concept:The law of diminishing marginal utility describes the behaviour of a consumer while enjoying successive units of a commodity.
Explanation:As a consumer consumes more units of a good, the extra satisfaction gained from each additional unit steadily falls.
This decline in marginal utility guides a rational consumer who aims to maximise total satisfaction from a limited income.
The consumer stops buying additional units when the marginal utility of the good equals its price, thereby reaching maximum satisfaction.
The law does not directly apply to a firm's cost minimisation or a producer's output maximisation.
It also does not describe a consumer who wants to minimise total utility, because rational consumers seek the highest possible satisfaction, not the lowest.
Answer:Consumer who maximizes satisfaction. (Option B)