What does the abbreviation "DDR" stand for?

EDITORIAL LEARNING AID

Why is this answer correct?

DDR stands for Deutsche Demokratische Republik (German Democratic Republic), the second German state from 1949 to 1990. The other abbreviations did not exist; "Third Reich" referred to the Nazi dictatorship. There was never a "Third German Republic".

DDR = German Democratic Republic.

This translation and explanation are editorial learning aids. The official German wording and answer key govern the examination.