handbook上面关于call swaption的论述跟我从其他渠道查到的不一样啊！handbook上call option的buyer有权pay floating and receive fixed，其他渠道是A call swaption allows the option buyer to enter into an interest-rate swap where the buyer of the option pays the fixed-rate and receives the floating-rate.

多做题就知道了
FRM里面的凡是涉及利率互换的 都是 receive fixed， pay floating,的

他是为了对冲利率上涨的风险 当然应该是pay fixed receive floating吧。

did you notice "flexibility"?

個人想法:
這題主要在講flexibility並沒有寫到Long/Short,所以如果是(Short) call swaption亦合理~!!