The correct answer is A. Law of utility and demand.
The rule of equimarginal utility states that a consumer will maximize their utility by allocating their income in such a way that the marginal utility of each good is equal. This is also known as the law of diminishing marginal utility, which states that the marginal utility of a good decreases as the consumer consumes more of that good.
The law of utility and demand is a different concept. It states that the demand for a good is inversely related to its price. This means that, as the price of a good decreases, consumers will demand more of it, and vice versa.
The rule of replacement is a concept in accounting that states that assets should be replaced when their book value is less than their replacement cost.
The indifference rule is a concept in economics that states that a consumer is indifferent between two bundles of goods if they provide the same level of utility.
The law of economy in expenditure is a concept in economics that states that consumers will try to maximize their utility by spending their money in the most efficient way possible.
Therefore, the only option that is a mismatch is A. Law of utility and demand.