The most effective claim for Nate's argument is:
"Our school should not have a football team because research shows that twenty percent of students will suffer at least one concussion during their high school playing career, which can have dangerous and permanent effects."
This claim is effective because it uses specific statistics and emphasizes the serious health risks associated with playing football, providing a strong factual basis for the argument. It directly addresses the safety concerns that are central to Nate's thesis, making it the most compelling choice.