To summarize the central idea in a text, readers should identify the topic and then identify
o
little-known facts about the topic.
the author's opinion about the topic.
other readers' opinions about the topic.
scientific facts about the topic.

Step 1:  Determine which options are correct

To summarize the central idea in a text, readers should identify the topic and then identify

- Option B:  the author's opinion about the topic.

The reason why Option B is correct is because that is the an important detail to add for the summarization of a text.  It is not Option A because little-known facts are not important in a summarization.  The reason why Option C isn't an answer is because a summarization does not include other opinions.  Finally, the reason why the answer isn't Option D is because there is no point of having scientific facts about the topic.  

See the attachment for clarification

you shopuld find your answers here if you need more. the answer is the infinite variety of human nature