What is the head of government of Saarland called?

EDITORIAL LEARNING AID

Why is this answer correct?

The head of government of Saarland is called Minister President and is elected by the state parliament. "First Minister" and "Prime Minister" are titles used in other countries, and a mayor heads only a city or municipality.

Saarland: Minister President, elected by the state parliament.

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