Suppose that in a country people gain more confidence in the banking system and so hold relatively less currency and more deposits. as a result, bank reserves

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.

It would be answer a