The author introduces the concept of class pictures in order to

A． illustrate photography's capacity for recording a historical moment
B． provide an example of photography that appears only to record but actually imposes aesthetic standards
C． demonstrate one area where photography is clearly more functional then painting
D． establish a case where photography is "transparent", i.e. independent of the photographer's aims
E． give an instance where photography is capable of democratizing an experience by converting it to an image