At a general election for a university student union, Zhang Hua and four other contenders registered for the chairmanship of the student union. None of the other four contenders had all the advantages of Zhang Hua. Which of the following conclusions can be logically drawn from the above conclusions? ['The other four candidates have some disadvantages.', 'Zhang Hua is the best student and has the qualifications to be elected chairman of the Student Union.', 'The other four candidates are not as good as Zhang Hua.', 'Zhang Hua has all the advantages of the other four candidates.']