Why are investors willing to buy German government bonds with a negative interest$$ rate?

A$.$

They believed that there was no chance the German government would default on its$$ bonds, while the default risk on corporate bonds and bank deposits was high because interest rates were so low.

B$.$

Concerns over the stability of the European Central Bank meant that German bonds were more attractive to investors.

C$.$

They believed that there was no chance the German government would default on its$$ bonds, while the default risk on corporate bonds and bank deposits was high because interest rates were so high.

D$.$

Other countries were defaulting on their$$ bonds, while Germany was not.