The “hook” is the opening sentence that grabs the readers attention.
the answer is most likely the first sentence
You could pose questions ...
"What does it mean to be an adult? Is it based on age? Is it based on employment? Is it a gut feeling? More important perhaps than these questions, is how the sense of being an adult helps one assume a larger role in our society."
I'm not sure exactly how you plan to go about your paper or what ideas you are exploring within your writing, so this might not work entirely. Nevertheless, I think it could be a good place for you to start.
Anne Frank starts off nervous and scared but over time Anne learns to have hope and faith that in the end everything will be ok.
