Who pays for social insurance in Germany?

EDITORIAL LEARNING AID

Why is this answer correct?

Social insurance contributions are in principle paid half by employers and half by employees. Neither side alone (b, d) bears them, and all nationals (c) pay only if they are employed and insured.

Employers and employees each pay half of social insurance.

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