Gotta make the spaces between the answers a different colour or something. After filling in Bolivia and Paraguay, I racked my brain for a good 30 seconds trying to find a third landlocked South American country
I believe that Kosovo was part of Serbia when Yugoslavia disbanded. It became independent of Serbia after the dissolution so the quiz maker is correct not to include it here.
Calling it Macedonia should be good enough, that is what it was called when it came out of Yugoslavia, and the answer including North could also be accepted. Not accepting Kosovo makes sense, it wasn't its own country before forming Yugoslavia, and didn't exist until splitting of from another post-Yugolaslav state. So geographically it might have been, but politically not.