In the Context of Strategies to Govern Metropolitan Regions, What

In the context of strategies to govern metropolitan regions, what is meant by agreements to furnish services?

A) It refers to the practice of large cities absorbing neighboring areas into it.
B) It refers to the practice of a few cities sharing a single activity.
C) It refers to the practice of multiple cities establishing an authority to run services in all the cities.
D) It is the practice of establishing units of government to provide one or more particular services for a regional area.
E) It is the practice of merging with the surrounding county's government.