If you could pitch me one idea for a book,what would it be?

The hiring authority wants to get to know you. One great way to do this is to ask about your interests. Generally speaking, you would want to pitch something you are knowledgeable in and passionate about. There is no right or wrong answer to a question like this; however, the interviewer will want to see that you are insightful and have enthusiasm for an exciting topic. If you choose an item that is related to HarperCollins or their publication, that's great but certainly not a requirement for this to be a successful answer.