要对下列CSS代码进行缩写,符合缩写的规范是的() background-position: 0 0; background-repeat: no-repeat; background-image: url(aa.gif)
A.background-image: url(aa.gif) no-repeat 0 0;
B.background-url: aa.gif no-repeat 0 0;
C.background: url("aa.gif") no-repeat 0 0;
D.background: aa.gif no-repeat 0 0;