A researcher posts a newspaper advertisement offering $10 in exchange for participation in a short study. The researcher accepts the first 10 people who respond to the advertisement. Which of the following statements is true about the sample? (5 points) Group of answer choices

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

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

It is a valid sample because the first 10 people were selected to participate.

It is not a valid sample because it is not a random sample of the population.