What resource from the north sea is the most important for the economies of europe? a) oil b) fish c) gold d) coal

I believe the answer for this is Fish.

River arrow on this map is pointing

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.