Define public health.

The definition of public health revolves around the protection and improvement of community health. This encompasses a broad range of activities and practices aimed at preventing disease, prolonging life, and promoting health through organized efforts at the community level. Public health initiatives focus on populations rather than the individual, addressing health issues through education, policy-making, and research to create environments conducive to health.

In contrast to the other options, which have narrower focuses, the selected answer aligns with the holistic approach of public health. For example, studying individual illnesses focuses on the clinical aspect rather than community health. Researching pharmaceutical advancements, while important, does not encompass the broad scope of public health activities aimed at the overall well-being of populations. Similarly, the administration of health insurance pertains more to health care access rather than the proactive measures involved in fostering community health. Thus, the correct choice encapsulates the essence of what public health seeks to achieve.