A researcher posts a radio advertisement offering $35 in exchange for participation in a short study. The researcher accepts the first eight people who respond to the advertisement. Which of the following statements is true about the sample? A.)It is a valid sample because the first eight people were selected to participate. B.)It is not a valid sample because it is not a random sample of the population.C.) It is a valid sample because money was offered to participants.D.) It is not a valid sample because it is only a short study.