Who forms the German Bundesrat?

EDITORIAL LEARNING AID

Why is this answer correct?

The Bundesrat consists of members of the state governments, who represent their states (Art. 51(1) GG); depending on population, a state has three to six votes. Members of the Bundestag (a), federal ministers (b) and party members (d) are not members of it as such.

Bundesrat equals state governments, three to six votes per state.

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