What does the abbreviation CSU stand for in Germany?

EDITORIAL LEARNING AID

Why is this answer correct?

For the “Leben in Deutschland” test, connect “Christian Social Union” with the meaning of the question. This is the answer marked as correct in the official key. “Christian Secure Union” is not part of the solution and points to a different issue. Learn the key term together with the complete correct answer instead of memorising only its letter.

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