What must be stressed to all participants attending a health fair?

What must be stressed to all participants attending a health fair?
 
  a. A screening program is not a substitute for ongoing health supervision from a health care provider.
  b. All test results are only tentative, and so participants who receive negative test results may nonetheless be suffering from a disease.
  c. Results are true today, but disease can develop any time, so participants should attend any future health fairs as well.
  d. There are many other diseases that may be attacking participants that the health fair did not screen for, and so continued vigilance is necessary.