Adandruff shampoo claims it can eliminate all dandruff flakes for 6 months. which would be a good strategy for proving the claim is true? a.) ask the one person you know who used it to verify if it worked for her. b.) ask the cashier if a lot of people have purchased this product. c.) search online to see if the claims can be verified by scientific studies. d.) buy it and just test it yourself over the next 6 months.