What caused flooding in the indus river valley?
a) tornadoes
b) heavy rains
c) monsoons and melted ice from the mountains
d) tidal waves and beach erosion

The repetition of initial consonant sounds is called alliteration

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.