"Of" is a preposition in the phrase "Of studying" and "until" is another, as well as "to" in the phrase "to college" so there are 3 in that sentence.
I think that the subject of the excerpt is c) Mathilde's discontent with her humble lifestyle because she compared her life to a rich one, one she felt that she was meant to have.
Answer:
I need a bit more information if u want a correct answer
