题目选项分析

Which of the following most logically completes the passage?

Most bicycle helmets provide good protection for the top and back of the head, but little or no protection for the temple regions on the sides of the head. A study of head injuries resulting from bicycle accidents showed that a large proportion were caused by blows to the temple area. Therefore, if bicycle helmets protected this area, the risk of serious head injury in bicycle accidents would be greatly reduced especially since _________.

【选项】among the bicyclists included in the study's sample of head injuries, only a very small proportion had been wearing a helmet at the time of their accident