One of the adults at a health education program introduced a rather unorthodox suggestion, claiming, ...

One of the adults at a health education program introduced a rather unorthodox suggestion, claiming, I saw it on the Internet. Which of the following criteria is most important for laypeople to use in deciding whether to accept information on the Intern
 
  a. The author of the information has written several books on the topic, all of which are for sale.
  b. The content of the site is supported by an international pharmaceutical company.
  c. The site is frequently referred to in magazine and TV advertisements.
  d. The site is maintained and frequently updated by a federal health agency.