Which of the following statements regarding provisions for paying off bonds is least likely correct（）

A. Nonrefundable bonds can be callable.

B. Serial bonds are an issue with several staggered maturity dates.

C. A sinking fund provision gives the company the option to retire portions of the bond issue prior to maturity.

拟话本小说的体制包括题目、篇首（）六个部分。

A、入话

B、头回

C、正话

D、结语

E、篇尾