[单选题]贯通地线或电气化区段的长途电缆、地区电缆屏蔽地线的接地电阻值应不大于()Ω。
A.1
B.2
C.3
D.4

背景
某企业新建厂区办公楼，建筑面积2605m2，为3层框架结构，混凝土空心砌块砌筑。现结构及砌筑均已施工完毕，外墙抹灰已完，按经监理审核通过的施工方案拆除外脚手架，然后用吊篮进行外墙饰面防水涂料涂刷。
脚手架拆除作业：本建筑平面形状为细长条，脚手架按东、南、西、北四个立面分片进行拆除，先拆除南北面积比较大的两个立面，再拆除东西两个立面。由于架子不高，同时为了快速拆除架体，工人先将连墙件挨个拆除后，再一起拆除架管。拆除的架管、脚手板直接顺着架体溜下后斜靠在墙根，等累积一定数量后一次性清运出场。脚手架拆除完毕后，涂饰工人在休息室内开始调料操作，并提前打开所有门窗，确保通风顺畅。
屋顶为上人屋面，正在进行屋顶周边钢管护栏的施工。安全总监详细核查高处作业人员的身体状况及以往病史，确认安全后才允许临边施工作业。

We have more genes in common with people we pick to be our friends than with strangers. Though not biologically related, friends are as "related" as fourth cousins, sharing about 1% of genes. That is 1 a study publishedfrom the University of California and Yale University in theProceedings of the National Academy of Sciences, has 2 . The study is a genome-wide analysis conducted 3 1932 unique subjects which 4 pairs of unrelated friends and unrelated strangers. The same people were used in both 5. While 1% may seem 6 , it is not so to a geneticist. As co-author of the study James Fowler, professor of medical genetics at UC San Diego says, "Most people do not even 7 their fourth cousins but somehow manage to select as friends the people who 8 our kin." The team 9 developed a "friendship score" which can predict who will be your friend based on their genes. The study also found that the genes for smell were something shared in friends but not genes for