Final answer:
North Carolina law requires an observer to be on board a PWC in addition to the operator if the PWC lacks a rearview mirror and is towing a skier.
Step-by-step explanation:
According to North Carolina law, when a Personal Watercraft (PWC) without a rearview mirror is towing a skier, there must be an observer on board in addition to the operator. The observer's role is to watch the skier at all times and communicate with the operator to ensure the safety of the skier. If the PWC is equipped with a rearview mirror, the observer may not be required, but for PWCs without this equipment, the presence of an observer is a legal necessity.