Australia’s agricultural and sheep-raising endeavors have suffered greatly due to a. monsoons b. overpopulation of rabbits c. overpopulation of kangaroos d. atomic tests

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.