Which of the following procedures would provide a researcher with a truly random sample of 15 participants?
Selecting every 5th name from an alphabetical directory of 75 students.
Recruiting 15 volunteers who respond to a flyer posted in a local community center.
Generating 15 random numbers to select participants from a numbered database of 150 students.
Choosing the first 15 individuals who walk through the main entrance of a university department.
