Answer:
The correct answer is the last on that’s states: it is not a valid sample because it is not a random sample of the population.
Step-by-step explanation:
When a researcher wants to know about the same thing, he/she has to take a sample from the population.
Example, consider a researcher wants to know how many hours the students study at home in a week, so the researcher has to take the sample from the student population.
Here, he/she gives the advertisement and offers $10 for 10 people. Therefore for anyone can come they might not required for a particular study.
Therefore, the answer is the last one.
