上述描述定义，属四型观测线是（）

A．基牙向缺隙相反方向倾斜时所画的观测线

B．基牙向颊侧或舌侧倾斜时所画的观测线，基牙的近、远缺隙侧均有明显倒凹

C．基牙向缺隙方向倾．斜时所画出的观测线

D．基牙向颊侧或舌侧倾斜时所画出的，但基牙的近、远缺隙侧均投有明显倒凹

E．基牙向缺隙方向或者反缺隙方向极度倾斜时形成的，观测线一端接近方，另一端接近基牙颈部

They do not think how much money they can make from a song；      ,they sing for their emotions and

live for music. [ ]

A. however      

B. therefore      

C. anyway        

D. instead