问题如下：
When classified by type of issuer, asset-backed securities are part of the:
选项：
A. corporate sector.
B. structured finance sector.
C. government and government-related sector.
解释：
B is correct.
Asset-backed securities (ABS) are securitized debt instruments created by securitization, a process that involves transferring ownership of assets from the original owners to a special legal entity. The special legal entity then issues securities backed by the transferred assets. The assets’ cash flows are used to pay interest and repay the principal owed to the holders of the securities. Assets that are typically used to create securitized debt instruments include loans (such as mortgage loans) and receivables (such as credit card receivables). The structured finance sector includes such securitized debt instruments (also called asset-backed securities).
B为什么是按照issuer分类的一种？这个是在哪里提到的呢
这个是在去年的讲义里面的，今年的讲义稍微做了修改，