问题如下：
Which of the following measures are most likely to be used by a securitized product backed by student loans?
选项： Single monthly mortality (SMM),
constant prepayment rate (CPR), and Public Securities Association (PSA).
Loss curves and absolute prepayment speed (APS).
C.Weighted average life (WAL), weighted average maturity (WAM), and weighted average coupon (WAC).
D.Debt service coverage ratio (DSCR) and monthly payment rate (MPR).
解释：
A The constant prepayment rate (CPR) and the Public Securities Association (PSA) method are common methodologies used to estimate prepayments for student loans and mortgages.
student loan也算是一种信用贷款啊，应该更加考虑的是credit risk啊，smm
cpr考虑的都是prepayment risk啊
