Which coat of arms belongs to the federal state of Saarland?

EDITORIAL LEARNING AID

Why is this answer correct?

Picture 4 shows the state coat of arms of Saarland, introduced in 1957, which combines the historical coats of arms of the region, above all the Saarbrücken lion. Pictures 1, 2 and 3 show the coats of arms of other federal states and are therefore wrong.

Saarland: picture 4, coat of arms from 1957.

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