Final answer:
The question demonstrates the law of diminishing marginal utility, where Fran's increasing satisfaction from consuming more fruit lessens with each additional piece.
Step-by-step explanation:
The question refers to the concept of utility and marginal utility in economics. Specifically, it illustrates the law of diminishing marginal utility, which states that as one consumes more units of a good, the additional satisfaction or utility obtained from consuming each additional unit typically decreases. Using the example provided, Fran's utility increases as she consumes more pieces of fruit, but the rate at which her utility increases slows down with each additional piece. This can be observed from the given data: 1 piece of fruit gives 6 units of utility, 2 pieces give 10 units (an increase of 4 units from the first piece), and 3 pieces give 12 units (an increase of only 2 units from the second piece). This pattern demonstrates the law of diminishing marginal utility.