上颌前牙颈部的唇舌向倾斜方向为（）

A.中切牙向唇侧，侧切牙、尖牙向腭侧

B.中切牙、侧切牙向唇侧，尖牙向腭侧

C.中切牙、侧切牙向腭侧，尖牙向唇侧

D.中切牙向腭侧，侧切牙、尖牙向唇侧

E.中切牙、侧切牙和尖牙均向腭侧

Could you please tell me _____ ?         [ ]

A. how to solve the problem          

B. what to solve the problem

C. how solving the problem            

D. what solving the problem