Final answer:
The marginal utility of successive units of a good or service should always be compared against the added cost or price of the good or service.
Step-by-step explanation:
In economics, the statement that the marginal utility of successive units of a good or service should always be compared against the added cost or price of the good or service is true. This concept is based on the law of diminishing marginal utility, which states that as we consume more of a good or service, the additional satisfaction or utility we receive from each additional unit tends to decrease. Therefore, it is important for consumers to consider the marginal utility they will derive from consuming an additional unit of a good or service compared to the cost or price of that unit.