Which safety initiative is important for preschoolers when riding tricycles?

Protective gear is essential for preschoolers when riding tricycles because it significantly reduces the risk of injury in the event of a fall or collision. At this stage of development, children are still developing their coordination and balance, making them more prone to accidents. Wearing helmets, knee pads, and elbow pads provides an extra layer of safety that can help prevent serious injuries, such as head trauma or skin abrasions.

The other options do not align with best practices for ensuring the safety of preschoolers while riding tricycles. For instance, stating that no supervision is required neglects the important role that adult oversight plays in monitoring safe play and intervention when necessary. Limiting tricycle use to only indoors can restrict a child's opportunity to develop motor skills in a more diverse setting, while training wheels are typically associated with bicycles rather than tricycles, and would not be applicable in this context. Thus, emphasizing the use of protective gear is the most effective safety initiative for young children in this scenario.