你上面的空放错地方了,应为：
Immigrants have to adapt themselves culturally and physically to the new surroundings _ they have moved.
是的,只有 A 合适.这个句子是由两个句子拼接而成的：
Immigrants have to adapt themselves culturally and physically to the new surroundings.
They have moved into the new surroundings.
把这两个句子组成一个复合句,第二句就成了the new surroundings 的后置定语从句.关系代词 which 取代 the new surroundings,引出从句作 into 的介词宾语.
其它答案语义不符.