Final answer:
Baseball is the youth sport that accounts for 2.8% of concussions. Concussions are common in many sports, with steps being taken by organizations to lower these risks through proper equipment safety ratings.
Step-by-step explanation:
The youth sport that constitutes 2.8% of concussions is baseball. Concussions are a mild but common type of brain injury that can cause temporary issues such as headache, drowsiness, and confusion. While contact sports such as football are often associated with a higher rate of concussions, other sports including baseball can also pose risks. Measures are being taken by institutions like the NCAA and NFL to reduce concussions, making it relevant to consider the safety ratings of equipment like helmets used across all levels of sports. However, the question specifically asks about the youth sport that constitutes 2.8% of concussions, so we need to find the sport that falls within this percentage.