题目解析:
对应原文:Studies by Park, Burgess, and other Chicago-school sociologists showed how new groups of immigrants tended to be concentrated in separate areas within inner-city zones, where they sometimes experienced tension with other ethnic groups that had arrived earlier.
从they后面跟着的内容来看,可以推出they指代的一定是人,而在前文中出现的人物有Park, Burgess, and other Chicago-school sociologists和new groups of immigrants。在这两个当中作抉择,而从内容上来看,how引导的从句和where引导的从句并列,所以后面的they指的就是new groups of immigrants,对应选B。