中国人民银行应将开户许可证作为重要空白凭证进行管理，建立健全开户许可证的（）制度。

A.印制

B.保管

C.领用

D.颁发

E.收缴

F.销毁

Which of the following is least likely to be the long-run effect of a price ceiling that is set below the equilibrium price（）

A. Sellers take bribes.

B. Suppliers discriminate.

C.Sellers improve quality.