问题如下图：
选项：
A. 
B. 
C. 
解释：
老师你好，这道题目考察的知识点怎么理解呢，谢谢解答
NO.PZ2018062012000009问题如下In a sequential-pCMO, the longer-term tranche investors will have the lowest:A.extension risk. B.average life. C.contraction risk. C is correct.For a sequential-pCMO, the longer tranche term will leto a lower contraction risk because of the protection against this risk offerethe other tranches. The longer-term tranche investor is likely to have a higher average life anextension risk because it is the last tranche repaiin a sequential-ptranche. 考点sequential-pCMO解析contraction risk是缩期风险，extension risk是延期风险。长期tranche，是最后一个还款的层级，存续期最长，面临的也是延期风险。本题问的是长期tranche的投资者什么最低，所以C正确。 视频课上老师给A写了一个contraction risk c 写了一个extension risk层级一是long term 层级三是short term 顺序支付是每个层级同时收到利息，本金先给层级一，直到层级一收到全部本金后，才开始归还层级二，最后归还层级三。这么理解有什么问题？谢谢老师我看了那个问题还是没懂。
average life. contraction risk. C is correct. For a sequential-pCMO, the longer tranche term will leto a lower contraction risk because of the protection against this risk offerethe other tranches. The longer-term tranche investor is likely to have a higher average life anextension risk because it is the last tranche repaiin a sequential-ptranche. 老师问下 这个cmo不是对prepayment的重新打包和分配吗 那有钱了先还最长期的 他不是面临很高的缩期风险吗 有点搞糊涂了 这道题不是很理解
average life. contraction risk. C is correct. For a sequential-pCMO, the longer tranche term will leto a lower contraction risk because of the protection against this risk offerethe other tranches. The longer-term tranche investor is likely to have a higher average life anextension risk because it is the last tranche repaiin a sequential-ptranche. 这道题可以具体一下嘛。tranche是贷款中的一个分层。为什么long term tranche 本金还的慢一些，耗费时间久，所以有extension risk. 这个逻辑对吗？Short term tranche 短期的，本金换的快，有reinvt risk 为啥是contaction risk?
根据之前的讲解，长期应该有更小的extension risk 啊
