Xiao Zhang must want to apply for a middle school, because all primary school students who want to apply for a middle school participate in the winter camp organized by the middle school, and Xiao Zhang participates in the winter camp organized by the middle school. Which of the following judgments best strengthens the above argument? ['All students who want to participate in the winter camp organized by the middle school want to apply for the middle school.', 'Some elementary students who do not want to apply for the middle school also participated in the winter camp organized by the middle school.', "Xiao Zhang's performance in 6 years of elementary school has been excellent.", 'Xiao Zhang attended the winter camp hosted by the middle school because his parents strongly advised him to attend.']