What is primarily a task of the federal states in Germany?

EDITORIAL LEARNING AID

Why is this answer correct?

Under Art. 30 and Art. 70 GG, schools and education are the responsibility of the federal states, which is why there are 16 different school systems. Defence (a) and foreign policy (b) are federal tasks, and economic policy (c) is shaped mainly by the federal level and within the European Union.

Schools and education are a matter for the states, not the federation.

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