Acontinental shelf is characterized by all of the following except:
a. abundant life
c. high amounts of sunlight
b. shallow water
d. steep drop offs

A continental shelf is characterized by all of the following  except abundant life. The correct option among all the options that are given in the question is the first option or option "a". Since it is the shallow part, so there is little chance of abundance of life. It also has very steep drop offs. It also gets an abundance of sunlight.

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.