Read the section "Scientists Track Head Hits To Get Answers." Which sentence explains WHY scientists put sensors in football players’ helmets?
A-About one in four kids had played football at least two years in a row.
B-Concussions can lead to headaches, dizziness and forgetfulness.
C-From this, the team could tell how many times each kid’s head had been hit.
D-The scientists teamed up with 195 boys who played football.
