Question

what the text is all about is...
○ the central idea.
○ nonfiction.
○ the evidence the author uses.
○ the supporting details.

Explanation:

The phrase "What the text is all about" directly refers to the main or central message of the text, which is the central idea. Nonfiction is a genre, evidence supports the idea, and supporting details are specific elements that back up the central idea—none of these match the description of what the text is entirely about.

Answer:

the central idea.