Critical Reasoning: Acme brand aspirin claims to be the best headache relief available on the market today. To prove this claim, Acme called 10 people and asked them their thoughts on headache relief products. All 10 of them stated that they unequivocally use Acme brand aspirin on a regular basis and that they believe it to be the best headache relief available on the market today. Which of the following would most weaken this argument?