Which of the following is a warning sign of fatigue while riding?

Answer: B — Frequent yawning and heavy eyelids

Frequent yawning and heavy eyelids serve as clear indicators of fatigue while riding. These signs reflect physiological responses to drowsiness that can compromise a rider's alertness and reaction time. When a person is feeling tired, the body's natural response often includes yawning, which is associated with the need for more oxygen and can indicate that the brain is seeking a state of alertness. Heavy eyelids can also be a strong signal that the individual is struggling to maintain alertness, making it risky to operate a motorcycle. Being aware of these signs is crucial for safety, as fatigue can lead to decreased concentration, slower reflexes, and an increased risk of accidents. Maintaining a high level of awareness and vigilance is essential for safe riding; thus, recognizing and addressing fatigue promptly is vital for a safe riding experience.