Wll give 20 points A researcher posts a print advertisement offering $20 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? (1 point)

Group of answer choices

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.

It is a valid sample because money was offered to participants.

It is not a valid sample because it is only a short study.