Mundane meaning: lacking interest or excitement; dull.
Inconsequential meaning: not important or significant.
Florid meaning: elaborately or excessively intricate or complicated.
Restrained meaning: kept under control; prevented from freedom of movement or action.
C is the answer because it is the best fitting. It is very descriptive but that doesn't mean that a lot of the words were significant or important. You could guess this is the answer due to the fact that it is very wordy, and not all of it might be important/significant.
Simply put, a biography is the life history of an individual, written by someone else. An autobiography is the story of a person's life, written by that person
