Some jurists are graduates of the Department of Economics of the University, so some graduates of the University of Economics are people who are very knowledgeable about the business of lawyers. Which of the following, if true, will guarantee the correctness of the above statement? ["Some jurists who have a good understanding of lawyers' business are not graduates of the Department of Economics.", 'Everyone who studies the lawyer business is a jurist.', 'Some jurists are not graduates of the Department of Economics of the University, but law students.', 'All jurists are very knowledgeable about lawyers.']