Jill Biden is dismissing any concerns about President Biden's mental fitness, calling them "ridiculous." "I think that's ridiculous," Biden says in an interview for this week's "CBS Sunday Morning." Portions of the sit-down at Camp David with Rita Braver were released Thursday. Biden shook her head as Braver asked about some recent polling that the CBS News journalist described as showing "quite a few Americans have some questions about the president's current mental fitness." A Politico/Morning Consult survey conducted last month found that only 46 percent of respondents agree that 79-year-old Biden "is mentally fit," while 48 percent disagreed. Biden...