问题如下图：
选项：
A. 
B. 
C. 
解释：
这道题为什么不选C呢，还有A选项是什么意思
NO.PZ2017121002000006 问题如下 Whitype of sovereign bonhthe lowest interest rate risk for investor? A.Floaters B.Coupon bon C.scount bon A is correct.Floaters are bon with a floating rate of interest thresets periocally baseon changes in the level of a referenrate. Because changes in the referenrate reflechanges in market interest rates, prichanges of floaters are fless pronounceththose of fixerate bon, sucoupon bon anscount bon. Thus, investors holng floaters are less exposeto interest rate risk thinvestors holng fixerate scount or coupon bon.考点利率风险解析本题建议直接从久期的角度来考虑，因为ration代表的是债券价格对于利率变化的敏感程度。题目让我们选出利率风险最低的风险，换句话就是选出ration最小的债券。浮动利率的久期为重置期的一半，接近零。因此浮动利率债券的利率风险最小，故A正确。 老师您好，我已经学过久期这个章节。但是对“浮动利率的久期为重置期的一半，接近零”还是无法理解。问题一（1）可以请老师详细的展开一下这句话吗？问题二（2）浮动债券的久期如何计算？未来现金流不确定的情况下，浮动债券的是否无法用修正久期计算？那么应该如何计算呢
这题完全不知道选哪个。。请问哪课有学过呀？
Coupon bon scount bon A is correct. Floaters are bon with a floating rate of interest thresets periocally baseon changes in the level of a referenrate, suLibor. Because changes in the referenrate reflechanges in market interest rates, prichanges of floaters are fless pronounceththose of fixerate bon, sucoupon bon anscount bon. Thus, investors holng floaters are less exposeto interest rate risk thinvestors holng fixerate scount or coupon bon.scount boun什么？讲义里有讲过么？
Coupon bon scount bon A is correct. Floaters are bon with a floating rate of interest thresets periocally baseon changes in the level of a referenrate, suLibor. Because changes in the referenrate reflechanges in market interest rates, prichanges of floaters are fless pronounceththose of fixerate bon, sucoupon bon anscount bon. Thus, investors holng floaters are less exposeto interest rate risk thinvestors holng fixerate scount or coupon bon.因为floaters 是随着market interest rate 变化而变化，不考虑interest rate 的volability，所以是low risk。老师 请问这一题我可以这么考虑吗？
A是浮动利率债券。浮动利率的久期为重置期的一半，接近零。Floater’s ration is half of reset perio因此浮动利率债券的利率风险最小。 老师 答案里的ration 视频里何老师没有提及 应该怎么理解？
