The two sources disagree on the effectiveness of recycling programs in schools. Source 1 emphasizes that the participation of school districts is necessary for recycling to have a positive impact on reducing greenhouse gas emissions, suggesting that large numbers of people can work together successfully. In contrast, Source 2 points out the challenges of getting all students to follow a specific recycling program, suggesting that this can lead to ineffectiveness.
Therefore, the correct response reflecting their disagreement is: "Successful recycling programs require the participation of many people."