What are the colours of the state flag of North Rhine-Westphalia?

EDITORIAL LEARNING AID

Why is this answer correct?

The state flag of North Rhine-Westphalia is green-white-red, with the state coat of arms in the centre. Red-white is the flag of Hesse, black-gold the flag of Baden-Württemberg and blue-white-red the flag of Schleswig-Holstein.

Green-white-red: Rhine, Westphalia, Lippe.

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