Which of the following describes primary prevention?

Primary prevention refers to measures taken to prevent the onset of illness or injury before it occurs. This level of prevention is focused on reducing risk factors and promoting health in order to avert diseases or health issues altogether. Examples include vaccination programs, health education, and lifestyle modifications such as encouraging a balanced diet and regular physical activity.

In contrast, other options describe different levels of prevention or health care approaches. Early diagnosis of an existing condition pertains to secondary prevention, which aims to detect and address health issues in their early stages. Rehabilitation after a serious illness relates to tertiary prevention, focusing on recovery and managing long-term impacts of a disease. Social support for chronic conditions involves ongoing support and care, which also fits under tertiary prevention as it helps in managing ongoing health issues rather than preventing them. Thus, the selection of measures to prevent illness or injury is central to the concept of primary prevention.