A would be correct because anything that works for someone else may or may not work for you. It's also clear that she's sharing what worked for her. But also C and D fit because she could provide advice about how to achieve your own goals and get a healthy lifestyle. The reason I would choose A over the rest is because the title of the book does not say she's providing advice on what to do or not do. She is just sharing her experience with you. It may or may not help you and it might be something you can try but might not work for you. The other two would assume too much and not enough information was provided to make the assumption.
The answer to this is C. Radiation Exposure.
