Which statement best describes how the sea affected travel in ancient Greece? Violent seas forced ancient Greeks to travel by land.
Ancient Greeks feared the sea as part of their religion.
The seas were used by Greek city-states to stay connected.
City-states used both land and sea routes for trade and travel.

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.