What would be an example of a formal region?

A nation is a formal region; it is a particular political entity and may have a common language. The Great Plains region is an example of a landform region; it too is considered a formal region. Functional regions are organized around a focal point; the metropolitan area of New York City is an example.

d. stage 4

explanation:

the existence of some kind of demographic transition is widely accepted in the social sciences because of the well-established historical correlation linking dropping fertility to social and economic development.[1] scholars debate whether industrialization and higher incomes lead to lower population, or whether lower populations lead to industrialization and higher incomes. scholars also debate to what extent various proposed and sometimes inter-related factors such as higher per capita income,lower mortality, old-age security, and rise of demand for human capital are involved.[2]