What case would not be heard by a federal court
a: plaintiff: foreign corporation and defendant: u. s. government
b: plaintiff: private citizen and defendant: state
c: plaintiff: one state and defendant: another state
d: plaintiff: private citizen and defendant: u. s. government

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.