Which of the following statements about the German two$-$tiered board structure is true?

a$.$ Proponents of the German structure suggest that it helps prevent corporate wrongdoing and rash decisions by "dictatorial CEOs."

b$.$ The corporate governance practices in Germany make it easier to restructure companies more quickly.

c$.$ All German firms are required to have a two$-$tiered board structure.

d$.$ Critics of the German structure maintain it allows inside managers to dominate a firm's board of directors.