Read the definitions below and then answer the question that follows.
Watershed: A region in which all rainfall eventually flows downhill through a system of streams and tributaries into the same body of water, such as the catchment basin of a river or lake.

Milkshed: A region in which fresh milk is produced and can be delivered without spoilage for sale and consumption. A dairy farm sits at the center of an area, the size of which is determined by how far fresh milk can be shipped and still maintain shelf-life for consumers.

Given the definitions, watersheds and milksheds can best be classified as what type of region?

a. culture
b. formal
c. functional
d. industrial
e. vernacular