Final answer:
Healthy People 2020 is best described as a national agenda of health objectives aiming to improve the health and well-being of all Americans through specific, evidence-based benchmarks.
Step-by-step explanation:
The description that best represents Healthy People 2020 is a national agenda of health objectives. This initiative was designed to provide direction and measurable objectives for health improvement during the first decade of the 21st century. It aims to increase the health and well-being of all Americans by setting specific, evidence-based benchmarks and monitoring progress over time.
It is not a California-specific initiative, a health insurance plan for people over 50, or a federal mandate on maternal and child wellness only, though improving women's and children's health is part of the broader objectives. Healthy People 2020 encompasses a wide range of health domains, including chronic diseases, infectious diseases, reproductive health, environmental health, and behavioral health factors. This comprehensive approach to public health aims to engage multiple sectors in efforts to improve the overall health status of the American population.