----Do you know what Miss Black does for a living?----I have

----Do you know what Miss Black does for a living?----I have no idea at all.I think she could be n
----Do you know what Miss Black does for a living?----I have no idea at all.I think she could be ____but a singer.
A anything B nothing
我觉得这两个选项都翻译得过去,为什么要选A呢,请具体解答,不要笼统
选anything翻译得话就是 她可以做任何事除了当歌手
选nothing翻译就是 她只能做歌手
nothing but=only anything but=not，为什么一定要选A呢