They didn't want the French to take over the area.
What did the planes have in common? they were all domestic flights heading towards the West coast, which means that they would have a great amount of fuel on them: this would increase the explosion and fire after the crashes. This was a likely reason for those and not other planes being chosen.
That the government's powers comes from the people.
I think the answer should be Normay, France, and Denmark. These countries were occupied by the Germans, but they where not 100% secure. There was the French resistance in France, the Danish resistance in Denmark and the Norwegian resistance in Norway.
Hope this Helps! :)
