【名词&注释】
牙髓炎(pulpitis)、医疗机构(medical institutions)、牙髓坏死(pulp necrosis)、牙髓钙化(dental pulp calcification)、卫生防疫机构(sanitary and epidemic prevention instit ...)、《传染病防治法》(law of communicable disease prevention ...)、前伸运动(protrusive movement)、牙髓变性(pulp degeneration)
[单选题]正常前伸运动(protrusive movement)的距离为
A. 8~10mm
B. 10~12mm
C. 12~14mm
D. 5~7mm
E. 7~9mm