问题如下：
The fixed-income market can be classified by type of issuer. Which type of issuer is the collateralized debt obligations belong to:
选项：
A.government and government-related sector.
B.structured finance sector.
C.corporate sector.
解释：
B is correct.
There are three bond market sectors: the government and government-related sector, the corporate sector and the structured finance sector. The structured finance sector includes asset-backed securities, collateralized debt obligations and other structured financial instruments.
老师，你好，我在2020的讲义里，都没有找到这个知识点，就算是按着bond market 分类，也是分成”national bond market", "eurobond market" 和 ”global bonds".
可以麻烦老师再详细解释一下这个知识点吗？
如果是按着three market sector 分类， 那么每个sector中都包含了什么类型的Bond？谢谢~
