Answer: b. Economic Region
Explanation: Economic Region is the region which is based on the work culture of a certain population. It is directly dependant on the kind of work people do belonging to that population. Whereas, cultural region is based on culture, vegetation culture is based on the vegetation in that specific area and lastly, climatic region is based on the climatic conditions prevailing in that area. Defining the economic region clearly is a primary step required for checking economic impact in any economic base analysis.