Final answer:
When a PHN compares rates of teenage pregnancy, they are implementing the policy development function of public health, which assesses and informs strategies to improve community health outcomes.
Step-by-step explanation:
When a Public Health Nurse (PHN) compares the rate of teenage pregnancy across various areas of the city, the core function of public health being implemented is policy development. This activity is an essential component of public health as it informs future decisions and helps create effective strategies to address health concerns. By examining the rates of teenage pregnancy, the PHN can evaluate the effectiveness of existing policies, such as sex education programs, and contribute to the development or refinement of new policies that aim to reduce teenage pregnancy rates.
For example, the findings could indicate whether comprehensive sex education programs are more effective compared to abstinence-only approaches. This assessment allows for systematic evaluations and can potentially alter public health policy cycles. Ultimately, the data gathered during such comparisons is instrumental for advancing health policies that better serve the community's youth and address public health issues.