为什么c不对，还是不理解

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.

考点：国债

解析：主权债券通常是国家政府发行的无抵押债券，直接以国家的信用作为担保。故选项A、B均不正确。它们没有抵押品作担保，而是由国家政府的税务当局担保。故选项C正确。