Politician: Of the candidates running, Thompson is the best person to lead this nation. For one thing, Thompson opposes higher taxes whereas the other candidates support them. Many would agree that anyone who opposes higher taxes will make a better leader than someone who supports them. Which one of the following, if true, casts the most doubt on the politician's argument? ['All of the past leaders who supported higher taxes were hardworking.', 'All of the past leaders who supported higher taxes performed their jobs adequately.', 'Being opposed to higher taxes is not a sufficient condition for good leadership.', 'Opposing higher taxes is not a factor contributing to good leadership.']