Which of the following is an example of primary prevention?

Primary prevention refers to strategies and activities designed to prevent a disease or injury before it occurs. The main goal is to reduce risk factors and promote health, therefore averting the onset of health issues.

Vaccination is a quintessential example of primary prevention. By administering vaccines, individuals are provided with immunity against certain infectious diseases. This proactive measure helps to prevent disease outbreaks and decreases the incidence of the illness in populations, effectively protecting not just the individual receiving the vaccine, but also the community through herd immunity.

In contrast, the other options refer to forms of secondary or tertiary prevention. Heart surgery typically addresses an existing condition rather than preventing one. Cancer screenings are aimed at early detection of cancer rather than prevention of the disease itself. Physical rehabilitation is focused on recovery from an existing injury or disease. Thus, vaccination is recognized as a fundamental practice in primary prevention strategies aimed at safeguarding public health.