Final answer:
Utility is difficult to measure because it is a subjective concept representing the satisfaction derived from consumption, and it is subject to the law of diminishing marginal utility.
Step-by-step explanation:
The statement that utility is difficult to measure quantitatively is true about utility. Utility represents the satisfaction or fulfillment that a consumer derives from consuming a good or service, and it is a subjective concept. While economists can assume that more consumption generally leads to more utility, they also recognize the principle of the law of diminishing marginal utility. This law states that as a person consumes more units of a good, the additional satisfaction obtained from consuming each further unit tends to decrease. Therefore, utility is not the same as usefulness, is not objectively determined, and total utility does not necessarily diminish as soon as additional units are consumed, but the marginal utility may diminish.