It would be C because it is the only one that you could write a full essay on. It makes it vague enough so that you can cover all the areas that you want to be able to prove and persuade the reader into also thinking that, that particular book is better than the author's other books. That thesis gives you your foundation so that then you can work from the ground up, and it makes it easier to persuade, because like I said, it's vague and you can include every single one of your points to be made into the essay. The other options focus too much on one minute detail of the story, that you wouldn't really even have an essay.
