A parent is researching childhood immunizations and finds two conflicting sources of information. Source A is a popular online forum that cites a single study from 1998 and features many personal stories from parents who believe a specific vaccine caused their child's developmental disorder. Source B is a summary from a national public health organization that references dozens of large-scale studies conducted over 20 years, all of which found no connection; it also notes that the 1998 study was retracted due to scientific misconduct. Which statement best analyzes the quality of evidence from these two sources?

Evaluating Health Information Sources