单项选择题

A.颅骨侧位片上,枢椎齿状突超过腭枕线1mm
B.颅骨侧位片上,枢椎齿状突超过腭枕线2mm
C.颅骨侧位片上,枢椎齿状突超过腭枕线3mm
D.颅骨侧位片上,颅底角大于12°
E.颅骨侧位片上,枢椎齿状突低于腭枕线1mm