From what age may one vote in local elections in Saarland?

EDITORIAL LEARNING AID

Why is this answer correct?

In Saarland, one may vote in local elections from the age of 18; the voting age there was not lowered to 16, unlike in North Rhine-Westphalia or Lower Saxony, for example. 14 and 16 are too young, 20 is too high.

Saarland: local elections from the age of 18.

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