Really, that depends on the story you're reading. The story wouldn't tell where the author is born, the author could've researched another country to make the character act the way they do, so you could quickly eliminate that answer. Sometimes you can tell what decision the character will make if the book is easily predictable, like usually in teen fiction. Imagine a book where there's a good girl, she's very shy. She meets a bad boy, a player. You can easily predict that they will get together. I doubt that you will figure out that there are multiple themes just by reading the exposition. The exposition is the introduction, there's so much more to read after that. The last one sounds more like it, in the exposition, it immediately introduces the main character. It shows you the personality of the main character.
