From what age may one vote in local elections in North Rhine-Westphalia?

EDITORIAL LEARNING AID

Why is this answer correct?

In North Rhine-Westphalia, all German citizens aged 16 and over who have lived in the municipality for at least three months may vote in local elections. 14 is too young, 18 applies to state and federal elections, and 20 is too high.

NRW: local elections from 16, state elections from 18.

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