Both the family and the society ________ exceptional children live are often the key to their growth

and development. [      ]

A. which  

B. what

C. in which  

D. that

患儿7岁，主诉左下后牙有龋洞，冷热疼痛，无自发疼。查：
6（--）深龋洞，叩诊（-），牙龈正常。X-ray示牙根未形成，未见病变。处理：去除大部分腐质，近中髓角去腐时穿髓lmm穿髓孔探疼，应选何种治疗方法（）

A.活髓切断术

B.直接盖髓术

C.拔髓术

D.根尖诱导成形术

E.封金属砷后根管治疗