All general managers who really care about employee welfare have proven to be superb general managers in management art; while general managers who really care about employee welfare first focus on solving the housing of young and middle-aged employees. Therefore, those who do not The general managers who focus on the housing of young and middle-aged employees are not general managers with superb management skills. In order for the above argument to be true, which of the following must be true? ['All superb general managers of management arts are general managers who care about employee welfare.', 'The housing problem of young and middle-aged employees is the most prominent issue in employee welfare.', 'The proportion of young and middle-aged employees has exceeded 90%.', 'All the general managers who first focus on the housing of young and middle-aged employees are general managers with superb management skills.']