Evaluating the Impact of Extracurricular Activities

In a recent editorial about the importance of extracurricular activities in high school, the author claimed, "Students who engage in sports, music, or clubs report higher overall satisfaction with their school experience compared to those who do not participate in any activities outside their regular classes." The author argues that this satisfaction reflects a more well-rounded education and encourages schools to invest more in these programs.

However, a skeptic responded, stating, "Just because students involved in extracurricular activities report higher satisfaction does not mean that it is the activities themselves that cause this feeling. It could be that more socially adept students simply choose to engage in these activities and are already happier than their peers."

Which of the following, if true, would most seriously weaken the skeptic's argument?