问题如下：
Sovereign bonds are best described as:
选项：
A.bonds issued by local governments.
B.secured obligations of a national government.
C.bonds backed by the taxing authority of a national government.
解释：
C is correct.
Sovereign bonds are usually unsecured obligations of the national government issuing the bonds; they are not backed by collateral, but by the taxing authority of the national government. A is incorrect because bonds issued by local governments are non-sovereign (not sovereign) bonds. B is incorrect because sovereign bonds are typically unsecured (not secured) obligations of a national government.
老师您好，想请教一下B为什么不对，谢谢
