Final answer:
In an informational text, an opinion expresses the author's judgment or belief, which differs from facts that are verifiable pieces of information.
Step-by-step explanation:
An opinion in an informational text expresses the author's judgment or belief. This contrasts with factual information, which is based on evidence and data that can be verified, whereas opinions are statements of personal belief or value. When reading an informational text, it's crucial to distinguish between what is fact and what is opinion, as well as to critique the reliability of the author and the sufficiency of evidence supporting their inferences and claims.