问题如下图：
选项：
A. 
B. 
C. 
解释：
不太记得这个知识点在哪里了，请老师指点一下. 谢谢
NO.PZ2018062020000029 问题如下 Comparewith theweighteaverage coupon rate of its unrlying pool of mortgages, the pass-through rate on a mortgagepass-through security is: A.lower. B.the same. C.higher. A is correct.The coupon rate of a mortgage pass-through security is callethe pass-through rate, wherethe mortgage rateon the unrlying pool of mortgages is calculatea weighteaverage couponrate (WAC). The pass-through rate is lower ththe Wanamount equto the servicing fee another ainistrative fees.考点mortgage pass-through security解析mortgage组成的portfolio，每一笔mortgage都有一个贷款利率，WAC就是portfolio的加权平均贷款利率，MPS的coupon rate就是pass-through rate。两者之间的差距就是服务费。所以pass-through rate通常都是小于WAC的，所以A正确。 快考试了，来不及复习了，谢谢
NO.PZ2018062020000029 the same. higher. A is correct.The coupon rate of a mortgage pass-through security is callethe pass-through rate, wherethe mortgage rateon the unrlying pool of mortgages is calculatea weighteaverage couponrate (WAC). The pass-through rate is lower ththe Wanamount equto the servicing fee another ainistrative fees. 考点mortgage pass-through security 解析mortgage组成的portfolio，每一笔mortgage都有一个贷款利率，WAC就是portfolio的加权平均贷款利率，MPS的coupon rate就是pass-through rate。两者之间的差距就是服务费。所以pass-through rate通常都是小于WAC的，所以A正确。 是说pass through rate产品没有服务费，而另一个有？
mortgage组成的portfolio，每一笔mortgage都有一个贷款利率，WAC就是portfolio的加权平均贷款利率，MPS的coupon rate就是pass-through rate。请问MPS不也是一堆贷款分层，和加权平均不是一样的意思吗？还有服务费是哪里来的呢？为什么MPS没有服务费呢?请教一下，不太明白哈
pass through rate只怎么理解
the same. higher. A is correct.The coupon rate of a mortgage pass-through security is callethe pass-through rate, wherethe mortgage rateon the unrlying pool of mortgages is calculatea weighteaverage couponrate (WAC). The pass-through rate is lower ththe Wanamount equto the servicing fee another ainistrative fees. 请问是哪个rate有服务费呢？
