I WASTED ALL MY POINTS FOR THIS QUESTION Why so most people in the four countries we studied live in urban areas?

Your

Urban areas always have a warm tropical climate.

There are more jobs in the factories and businesses of the cities.

Urban areas have more arable land in these countries.

carefully examine the map above. based on your knowledge of colonialism in africa, the area attributed to belgium on this map is most likely the democratic republic of the congo.

saving account is right

an informal structure in a bureaucracy would be something like so-called "office politics". where there's a formal structure set up for the organization, but then an informal subculture as well that has a way of organizing the bureaucracy further. this can be positive because it sets up an added degree of organization, albeit informal, within the bureaucracy.