问题如下图：
选项：
A. 
B. 
C. 
解释：
老师你好，这道题目是不是问哪个分层使得投资者免于遭受prepayment risk嚒，我觉得应该是c呀，就像老师上课讲的，cf过多，surport 把多余的都吸收了，自己承担了prepayment risk ，当cf不够时，它把所有的cf都让给PAC ，所以我觉得应该选C，谢谢
NO.PZ2018062012000010 问题如下 Whiof the tranches of a collateralizemortgage obligation (CMO) will have the lowest prepayment risk? A.A Ptranches B.inverse floating-rate tranche C.A support tranche A is correct.Ptranches have protection against both extension risk ancontraction risk, proving two-siprepayment protection.Support tranches expose investors to the highest level of prepayment risk anits promiseinterest rate is higher ththe Ptranche.Because the inverse floater pays a lower rate when interest rates go up, thus amplifying interest rate risk.考点CMO解析当本金偿还快于预期，support tranches会吸收掉所有超过预期的偿还部分。当本金偿还慢于预期，support tranches不接受任何本金偿还，全部让给PAC结构。PAC受到了有限的保护，抵御 extension risk 和 contraction risk，这种保护来自于support结构。相反，support tranche的两种风险是最大的。故A正确。 RT
inverse floating-rate tranche A support tranche A is correct. Ptranches have protection against both extension risk ancontraction risk, proving two-siprepayment protection. Support tranches expose investors to the highest level of prepayment risk anits promiseinterest rate is higher ththe Ptranche. Because the inverse floater pays a lower rate when interest rates go up, thus amplifying interest rate risk. Planneamortization class (PAtranches have limite(but not complete) protection against both extension risk ancontraction risk. This protection is provithe support tranches.这道题目的答案不理解
老师你好，这道题目之前有同学问了，但是我依然有疑问先看题目，题目问哪个分层使得投资者免于遭受prepayment risk。我选的C。就像何老师上课讲的，prepayment cash flow过多，support 把多余的都吸收了，自己承担了prepayment risk ; 当prepayment cash flow不够时，它把所有的prepayment cash flow都让给P，因此，真正起作用的应该是support tranche。这样理解对吗？P.S. 题目中support 的拼写错了，不是surpot，而是support
