以下url的域名是？http://www.xmgc360.com/_pages/courseroom/courseroom.html?ttag=pHTML5

A、www.xmgc360.com;
B、www.xmgc360.com/_pages/courseroom;
C、www.xmgc360.com/_pages/courseroom/courseroom.html;
D、www.xmgc360.com/_pages/courseroom/courseroom.html?ttag=pHTML5