Text 1 presents this claim: A software firm concludes that explaining its recommendation algorithm increases user trust because participants rated the system more favorably after reading a technical description of how it worked. Text 2 adds this evidence: Participants were paid a bonus for completing a comprehension quiz on the description, and favorable ratings rose only among those who earned the bonus. In an unpaid trial, the description did not change ratings. How does Text 2 weaken the firm's conclusion about explanation alone?