【名词&注释】
原发性肝细胞癌(primary hepatocellular carcinoma)、弥漫型(diffuse type)、肺结核空洞(pulmonary tuberculous cavity)
[单选题]正常三脑室宽约为()
A. ≤2mm B. ≤3mm C. ≤4mm D. ≤5mm E. ≤6mm