If I was tasked with this question, I'd approach it in quite a mechanical and mercenary way. First, identify all the offices the firm has around the world. Have that list? Great - those locations are one's you can't pick.
Now, as you have identified, there are probably several areas which you might have wanted to pick but now can't. Nevertheless, there will be options open to you. To identify the best options, consider the largest and most pertinent macroeconomic trends. What are those trends? Where (geographically) are they most keenly felt/going to be most keenly felt? What are the ramifications, commercially and legally speaking, of such a trend?
Once you have answered those questions, you should have not only identified certain geographical areas which you might want to 'select', but also good reasons for choosing them. Compare the areas you have selected with the list of offices NRF already has. If there are any mismatches - fantastic, you now have a country where you can argue NRF should set up an office, and a rough idea why they should set up that office. Do a little more research into that country - its microeconomic affairs etc. and there you have it: an answer that identifies a unique country for NRF to set up another office with justifications that are both on an international and a domestic level!