问题如下：
Which of the following is not the characteristic of commercial mortgage-backed security?
选项：
A.It carrys full faith and credit of the US government.
B.Investors in CMBS typically face balloon risk.
C.With CMBS, investors have considerable call protection either at the structure level or at the loan level.
解释：
A is correct.
Agency RMBS issued by Ginnie Mae are guaranteed by the full faith and credit of the US government.
c选项是什么意思呢
