Several studies indicate that regular exercise improves mental health and enhances cognitive function. In light of this evidence, Dr. Smith argues that implementing a daily exercise program in schools will lead to better academic performance among students. He believes that encouraging students to exercise regularly will not only improve their physical health but will also increase their focus and ability to learn. In response, a group of educators suggests that the increased academic performance could be attributed to better nutrition provided in schools rather than exercise.

Which of the following, if true, would most strengthen Dr. Smith’s argument that a daily exercise program in schools will improve students’ academic performance?