Which coat of arms belongs to the Free State of Saxony?

EDITORIAL LEARNING AID

Why is this answer correct?

The Saxon state coat of arms shows a shield divided into black and white, crossed by a green rue crown (crancelin); Image 4 shows this coat of arms. The other three images show the coats of arms of other federal states, which do not bear the rue crown. The green rue crown is the most reliable identifying feature of Saxony.

A green rue crown on black and white: that is Saxony.

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