What colours does the German flag have?

EDITORIAL LEARNING AID

Why is this answer correct?

The federal flag is black-red-gold; this is laid down in Article 22 paragraph 2 of the Basic Law. Red-white-black were the colours of the German Empire, and the other combinations do not correspond to any German flag.

Black-red-gold, since 1949.

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