问题如下：
Which of the following is most likely to raise the required YTM?
选项：
A. Call option.
B. The floor of a floating exchange rate.
C. Put option.
解释：
A is correct.
Call options are good for the issuer and raise the required YTM. On the contrary, a put option or a floor protects favor the bondholder, thus decreasing the required YTM.
请问B选项是为什么错呢