An area with things in common that can be proven and that are measurable

Formal region.

Explanation:

A region can be defined as an area on the Earth's surface that is physically set apart by definable characteristics or attributes from others.

There are mainly three types of regions;

1. Formal region: some examples are Germany, United States of America, Africa, Europe, China, Canada etc.

2. Functional region: an example is the Houston metropolitan area.

3. Perpetual or vernacular region: an example is the slums of Detroit.

Formal region also known as uniform or homogeneous region can be defined as an area with things in common that can be proven and that are measurable. These includes language, cultural values, economic activity, climate etc.

the correct answer is c.