Question

the evidence the author uses to explain, prove, and support their central idea is... the supporting details. the reasons why they are writing the text. the main ideas. nonfiction texts.

Explanation:

Supporting details are specific pieces of information (e.g., facts, examples, data) that authors use to explain, prove, and back up their central idea. The other options are incorrect: reasons for writing refer to purpose, main ideas are what the text is about (not evidence for them), and nonfiction texts are a genre (not evidence itself).

Answer:

A. the supporting details.