From what age may one take part in the election to the German Bundestag in Germany?

EDITORIAL LEARNING AID

Why is this answer correct?

In Bundestag elections one may vote from the age of 18 (Art. 38(2) GG, § 12 of the Federal Electoral Act). Age 16 (a) applies only in some state and local elections, and 21 (c) and 23 (d) are not age limits for federal elections.

Bundestag election: voting from the age of 18.

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