Consider the following argument: "Our new 'Everlast' brand batteries are superior because they are favored by 9 out of 10 professional athletes who endorsed them in our latest marketing campaign." What is the primary logical flaw in this argument?

✓ Correct Answer: Option C

The argument uses an appeal to authority, but professional athletes are not experts on battery superiority. Their 'favor' is likely due to endorsement fees, making their authority biased and irrelevant to the product's actual quality. While a small sample size is a flaw, the primary issue is the type of authority.