Which of the following is least likely a disadvantage of a callable bond to an investor The:（）

A. investor is exposed to reinvestment rate risk.

B. cash flow pattern of a callable bond is not known with certainty.

C. issue often offers a higher coupon rate than a comparable option-free bond.

（）基本体的特征是每个表面都是平面。

A、圆锥

B、圆柱

C、平面

D、多边形