Use this one:
Apps that keep users informed of their location at all times, such as a navigation app
In other words, you make a location manager and tell it to start doing updates. You don't have to do anything with those updates! But as long as this is happening - that is, as long as your app is continuing to do location updates in the background - your app is also allowed to use Core Motion in the background. This is not just a trick; it is official Apple policy as explained in one of the WWDC videos from a couple of years ago.