Xiao Li reports to his supervisor: "I think the client doesn't like our new proposal, so we must switch back to the old one." When the supervisor asks "What did the client say?", Xiao Li admits it was just his impression: "Because the client took three days longer than usual to reply to our email this time." Applying the three-step argument check, which type of evidence does Xiao Li most need to add?

Answer: A

• AThe client's specific evaluations of the proposal, or observable behavior showing whether the client has clearly expressed dissatisfaction✓ Correct. Xiao Li treats 'slow reply' as evidence of 'dislike,' but a slow reply could also be due to a business trip or internal approval processes. To test the conclusion that 'the client dislikes the proposal,' one must find direct feedback or behavior from the client.
• BWhether the client was away on a business trip when the reply was delayed✗ Incorrect. This is only one alternative explanation for the slow reply; even confirming a business trip would not directly show whether the client likes the proposal. What is truly missing is direct evidence about the client's attitude.
• CWhich design team created the new proposal✗ Incorrect. Who made the proposal has no logical connection to whether the client dislikes it; this is irrelevant information and cannot justify switching back to the old proposal.
• DHow much cost the old proposal saved the client last year✗ Incorrect. However cost-effective the old proposal was, this does not entail that 'the client dislikes the new proposal,' let alone that 'we must switch back immediately'; it sidesteps the conclusion that needs testing.