A researcher posts a newspaper advertisement offering 520 in exchange for participation in a short study. The researcher accepts the first five people who respond to the advertisement which
of the following statements is true about the sample?
It is not a valid sample because it is only a short study
It is a valid sample because money was offered to participants
It is a valid sample because the first five people were selected to participate
It is not a valid sample because it is not a random sample of the population