From what age may a person vote in local elections in Schleswig-Holstein?

EDITORIAL LEARNING AID

Why is this answer correct?

In Schleswig-Holstein the voting age in local elections is 16. A 14-year-old may not yet vote; 18 applies to Landtag and Bundestag elections, and 20 is not a voting age.

To the local elections at 16: in Schleswig-Holstein.

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