​A scientist asked four of her dentist friends if they thought the new Brand X sugar-free gum that she developed was effective. Three responded​ "yes." The scientist used the results to write a TV advertisement claiming that ​"3 out of 4 dentists prefer Brand X sugar-free gum​." Is this a valid​ inference? Explain. Use pencil and paper. Explain all of the factors that are necessary for an inference to be valid.

Is the inference​ valid? Explain. Choose the correct answer below.

A.​Yes, because 3 dentists said yes out of 4 who were asked.

B. No, because 3 dentists said yes out of 7 who were asked.

C. No, because the dentists asked are not a representative sample of the population of dentists.

D.​Yes, because the dentists asked are a representative sample of the population of dentists.

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