Viewers surveyed immediately after the televised political debate last year between Lopez and Tanner tended to think that Lopez had made the better arguments, but the survey respondents who reported that Lopez' s arguments were better may have been biased in favor of Lopez. After all, Lopez eventually did win the election. Which one of the following, if true, most seriously undermines the argument? ['Lopez won the election over Tanner by a very narrow margin.', 'Most of the viewers surveyed immediately prior to the debate said that they would probably vote for Tanner.', 'Most people in the live audience watching the debate who were surveyed immediately afterward said that they thought that Tanner was more persuasive in the debate than was Lopez.', 'The people who watched the televised debate were more likely to vote for Tanner than were the people who did not watch the debate.']