How do I answer a questions that begin with "To what extent"?

With "to what extent" questions, you are being asked to choose which factor is the most important in a given event or outcome. For example - let's say your question is asking, "To what extent is Napoleon III responsible for the unification of Italy in 1871?". Now - the question is asking you to analyse the role that Napoleon III played in the events leading up to the unification of Italy. This you must do. Then, think about at least two - three other factors that are responsible for the unification of Italy. This can include factors such as: role played by Garibaldi, Cavour, and the growing sense of nationalism. These three factors can be discussed and analysed after you've focused on Napoleon III. Now ask yourself, is Napoleon III really responsible? Was he more responsible than Garibaldi, or Cavour, or nationalism? This is essentially what the question is asking you to do. You need to decide whether YOU think that Napoleon III was really responsible, or not. Then once you've decided, explain why you think Napoleon III was/was not responsible. Make sure that you're argument is being supported by evidence (events, dates, statistics, names etc), and explain your choice. This is what "to what extent" questions ask you to do.