Final answer:
Option D best illustrates diminishing marginal utility, stating that consumer satisfaction decreases with each additional consumed unit of a good, like the third slice of pizza offering less enjoyment than the second.
Step-by-step explanation:
The concept of diminishing marginal utility is best illustrated by option D: A typical consumer will receive less satisfaction from consuming the third slice of pizza for lunch than from the second slice. This principle asserts that as a person consumes more units of a good, the additional satisfaction (utility) gained from each subsequent unit decreases. Hence, after enjoying the first slice of pizza, which provides a high level of utility, every additional slice will bring progressively less satisfaction, illustrating the law of diminishing marginal utility.