What is emphasized as a rule of outlining in the passage?

What is emphasized as a rule of outlining in the passage?
A、An idea should always be divided, even if there is only one point.
B、Each division/subdivision should include unrelated points.
C、Points within a division/subdivision should not be related to the topic.
D、Points within a division/subdivision should be related and support the topic/subtopic.
【正确答案】：D