【名词&注释】
体外受精(in vitro fertilization)、继发龋(secondary caries)、同源人工授精(artificial insemination by husband)、异源人工授精(artificial insemination by donor)、牙槽嵴顶(alveolar ridge crest)、釉牙骨质界、无性生殖(asexual reproduction)
[单选题]X线片上判断牙槽骨高度降低的标准是牙槽嵴顶
A. 与釉牙骨质界平齐
B. 到釉牙骨质界的距离小于1mm
C. 到釉牙骨质界的距离小于2mm
D. 到釉牙骨质界的距离大于2mm
E. 到釉牙骨质界的距离大于3mm