A mall distributes questionnaires at its complaint desk, and most respondents express dissatisfaction. Based on this, the manager concludes that customers are generally dissatisfied with the mall. Which of the following evaluations is most accurate?

Answer: B

• AThe sample is too small; one questionnaire is not enough to draw a conclusion.✗ Incorrect. Even if the sample size were large, the sample would still be biased because the distribution location is limited to the complaint desk, which skews the sample toward dissatisfied people. The problem lies in the source, not the size.
• BThe sample is biased; respondents at the complaint desk already tend to be dissatisfied.✓ Correct. Collecting opinions only at the complaint desk filters out normal customers, which is a typical case of sample bias.
• CThe manager mistakes a short-term fluctuation for a long-term trend; the complaints may have only recently increased.✗ Incorrect. The stem provides no time-based comparison or fluctuation data; the core issue is the unrepresentative sample source, not the time period.
• DThe manager only looks for supporting evidence and ignores counterexamples, selecting data that favors his own view.✗ Incorrect. The stem does not indicate that the manager actively selects data; instead, the sampling method itself is unrepresentative, which is a sample bias.