A. is the correct answer and it this because look at your prefix (beginning part) macro means large or long therefore if you put it into context THE STUDY OF THE ECONOMY AS A WHOLE.
hope this helps
Answer:
Urbanization: this is the process by which the population or urban areas increases, usually because people move out to the cities form rural areas.
Metropolitan area: an admnistrative divison consisting in a city, and its sorrounding areas.
Suburb: the area sorrounding a city that has a lower population density than the urban core, but a higher population density than a rural area.
The relationship between these three variables is very close. Urbanization is what drives the growth of both urban cores and suburbs, and a metropolitan area emerges when a city and its suburbs grow enough that they require a new special administrative division in order to coordinate local policies.