What is the driving regulation for motorcycles with an engine displacement of less than 125 cc on expressways?

Answer: B — They must not drive on expressways

Motorcycles with an engine displacement of less than 125 cc are not permitted to drive on expressways in Japan. This regulation is in place due to safety concerns, as smaller motorcycles may not be equipped to handle the higher speeds and traffic conditions typically found on expressways. The regulation helps to ensure the safety of all road users by maintaining a certain minimum performance standard for vehicles allowed on these high-speed roadways. By restricting smaller motorcycles, the law intends to reduce the risk of accidents that could arise from vehicles that may struggle to keep pace with faster traffic. This is why the correct answer indicates that these motorcycles must not drive on expressways.