It is our choice on which of those we wish to do. My hon. Friend is absolutely right that the extension of the implementation period needs agreement with the EU, and that is why I have described this as a choice. It is for us to say whether we wish the backstop or the implementation period to be extended, but she is absolutely right that the extension would be a matter for negotiation with the EU. If we get to that point, there would be arguments on both sides about which would be preferable for the UK, just as there would be arguments on both sides within the EU, because the backstop is not a situation the EU wants either.