Which information source would be unbiased in verifying or disproving a claim made by a diet pill advertisement?
the manufacturer's website
a pharmacist
a salesperson
the label on the product

A salesperson because they know nothing of the product except what it should do, not if it works or if it is right for you or side effects. I would recommend the other three if you wanted to get advice on the right diet pill for you.

Hope I helped :)

A Sales person because the rest have to do with someone or something you can find reliable information on a diet pill , but not a salesperson who most likely doesn't know anything in specific about it . Hope this helps ! :-)