Answer:
Sarah can evaluate the credibility of the sources by checking for the author's expertise, credentials, and the reputation of the website. In this case, Dr. Franklin Higgins is an emergency room doctor and his article is published on the website of the American Medical Association, which is a well-respected organization in the medical field. On the other hand, the anonymous commentary on Biker's Heaven lacks an author and does not provide any verifiable credentials, so it may not be considered as credible. Therefore, Sarah can use the article by Dr. Higgins as a more credible source for her research paper.