Which of the following is NOT a clue that a customer is underage?

Answer: C — Distinguished facial features

The choice stating "Distinguished facial features" is indeed the most appropriate answer because distinguished facial features do not reliably indicate a person's age. Age cannot accurately be assessed solely based on physical characteristics such as the clarity or prominence of facial features. These characteristics can vary widely among individuals of the same age or across different ages. In contrast, the other options provide hints that may suggest a customer is underage. For example, multiple layers of clothing might be worn to conceal age identification or potentially an underage drinker's attempt to hide their identity. High top sneakers without shoelaces may also indicate a juvenile style or choice, which is more common among younger patrons. Non-matching earrings could hint at a lack of attention to fashion norms often observed in older individuals, suggesting a younger demographic. These factors can all serve as cues for a server trying to assess the age of a patron.