The answer is C, Portugal. This is because they remained neutral during WW2.
This other answers are wrong, because,
A: The Sudetenland was annexed by Germany in 1938 after the Munich Agreement.
B: Czechoslovakia was also annexed (aside from Slovakia, which was made into a puppet government) shortly after the Munich Agreement.
D: The Germans annexed Austria during the Anschluss.
Hope this helps! :)