divide into,separate into 和separate into的区别

divide into,separate into 和separate into的区别
有一题,
Physiograpohically (在自然地理学上)the United States may be _______three major divisions（区）.
A divided from B divided into C separated from D separated into
这几个短语区分在哪呢?
一楼的回答不详细呢