I think it can be a book you have read in the past, right?
They never used to require that, so i am unaware.
Good book that could impact you? Try a book that made you decide to go into whatever ti is you want to study. E.g. the book, the Elegant universe, made you want to go into physics.
Whatever you choose, you need to have specific, explicit reasons how it affected you in a large way. Think about how many people are going to use war and peace. I would not recommend trying to be pretentious and choosing something like 'discipline and punish: the birth of the prison" by Foucault, because unless you did high school debate no one is going to believe you understood any of it.
Books like 'the stranger' can be fine, they are short, very fast reads, and they have mixed messages to people. I found the book empowering, but most find it limiting in its underlying ideology.
