These are countries by the day they gained their independence according to Wikipedia as of 7/5/2020 A.D. The link to my source is here: https://en.wikipedia.org/wiki/List_of_national_independence_days
Well, you never know. If we had a French style revolution right now they might want to shift away from the Gregorian calendar. It would then be useful to know if the quiz was made before the revolution.