单项选择题

A.左上?为坐标原点(0,0),右下?为(Screen.width,Screen.height)
B.右上?为坐标原点(0,0),左下?为(Screen.width,Screen.height)
C.左下?为坐标原点(0,0),右上?为(Screen.width,Screen.height)
D.右下?为坐标原点(0,0),左上?为(Screen.width,Screen.height)