Final answer:
The correct words to complete the sentence 'Regions are ____ defined by economic activities, while regions are defined by human attitudes.' are 'not, regions' (Option C). This choice establishes a contrast between types of regions by indicating that not all regions are defined by economic activities; some are defined by the attitudes of the people living in them.
Step-by-step explanation:
To correctly complete the sentence, we should select the option that logically fills the blanks. The sentence given is: "Regions are ____ defined by economic activities, while regions are defined by human attitudes." The statement suggests a contrast between the two clauses, which indicates that one type of region is defined one way, while another is not. Therefore, the correct choice would be the one that establishes this contrast. The word that fits in the first blank should imply that regions are typically defined by economic activities. In the second blank, we need a word that negates this definition for the other type of regions, which are defined based on human attitudes instead.
Given these considerations, the option that best completes the sentence is C. Not, regions. So, the completed sentence reads: "Regions are not defined by economic activities, while regions are defined by human attitudes." This indicates that some regions may instead be characterized by other factors, like human attitudes, contrasting with those primarily defined by economic activities.