During which activities should a properly fitted helmet be worn?

A properly fitted helmet is essential for protecting the head during activities that pose a risk of head injury, particularly those involving higher speeds or potential falls. Riding a motorcycle is one of the most critical situations where a helmet is required due to the significant risks involved, including the potential for serious accidents and head trauma. Helmets designated for motorcycle use are specifically designed to absorb impact and provide protection against injuries, adhering to safety standards that help safeguard the rider.

In contrast, while there are helmets designed for sports, they are not suitable for all activities, nor are they the primary concern in activities like walking or swimming. Walking typically does not involve the risk scenarios that necessitate a helmet, and swimming environments have different safety considerations that do not include head protection in the form of a helmet. Thus, the relevance and importance of wearing a helmet while riding a motorcycle stand out, making it the correct choice for this question.