Which of the following is a primary restriction of holding a motorcycle permit in Illinois?

Answer: C — Permit holders cannot ride after dark

In Illinois, one of the primary restrictions of holding a motorcycle permit is that permit holders cannot ride after dark. This restriction is designed to ensure the safety of new riders, as operating a motorcycle at night presents additional challenges such as reduced visibility and increased difficulty in assessing road conditions and potential hazards. By prohibiting night riding for permit holders, the state aims to provide them with an opportunity to gain experience and improve their skills during daylight hours when visibility is better and road conditions are often safer. The other options mention various aspects of motorcycle riding but do not reflect a primary restriction tied specifically to the permit holders' experience level and safety considerations. For instance, while wearing a helmet is indeed mandatory for motorcycle riders in Illinois to enhance safety, it applies to all riders, not just those with a permit. Similarly, permit holders are restricted from carrying passengers, which is true, but the specific restriction about riding after dark is put in place primarily to address safety concerns associated with the inexperience of permit holders. Therefore, this makes the nighttime riding restriction a significant focus for new motorcyclists in Illinois.