Final answer:
Encouraging women at a health fair to have an annual mammogram is an example of illness prevention.
Step-by-step explanation:
Illness prevention involves taking steps to reduce the risk of developing diseases. Out of the options given, encouraging women at a health fair to have an annual mammogram is an example of illness prevention. Mammograms are screenings that can detect early signs of breast cancer, allowing for early intervention and treatment. By encouraging regular mammograms, the risk of developing advanced stages of breast cancer can be reduced.