What is a crucial step in determining the reliability of a non-fiction text?

Assessing the credibility of the author is essential in determining the reliability of a non-fiction text because the author's qualifications, expertise, and reputation significantly influence the trustworthiness of the information presented. An author with a strong background in the subject matter, relevant experience, and a history of publishing reputable works is more likely to provide accurate and reliable insights.

In contrast to this, focusing on the length of the text does not inherently relate to its reliability, as both short and long texts can be well-researched or poorly sourced. Checking for grammatical errors, while it can impact the professionalism of a text, is not a direct measure of the reliability of the information itself. Similarly, looking for illustrations may enhance the text’s engagement or understanding but does not provide evidence of the factual accuracy or reliability of the content. Thus, evaluating the author's credibility stands out as the most critical factor in assessing a non-fiction text's reliability.