أَصَحِيحٌ هَذَا التَّقْرِيرُ؟
Is this report sound?
كَيْفَ تَثْبُتُ صِحَّةُ هَذَا التَّقْرِيرِ؟
How is this report shown to be sound?
The first question asks whether the claim holds and may receive “yes, it is sound” as an answer. The second requests grounds for accepting the claim and calls for a method or evidence. Confusing the two can produce an answer that is linguistically intelligible but fails to meet the hearer's actual concern.
An interrogative form alone does not decide whether a question is genuine, rhetorical, negative or confirmatory. In this dialogue, the request for proof is genuine. Any alternative rhetorical interpretation would require a different contextual clue.