Which politician stands for the "Eastern Treaties"?

EDITORIAL LEARNING AID

Why is this answer correct?

The Eastern Treaties with Moscow and Warsaw of 1970 were concluded by Federal Chancellor Willy Brandt and his social-liberal government. Helmut Kohl stands for reunification, Mikhail Gorbachev was the Soviet head of state, and Ludwig Erhard was chancellor during the economic miracle.

Eastern Treaties 1970 = Willy Brandt.

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